diff --git a/performance_tests.sh b/performance_tests.sh
index b400d9b..3f73b61 100755
--- a/performance_tests.sh
+++ b/performance_tests.sh
@@ -38,7 +38,10 @@ DESCRIPTION
     TEST7: classic fetching and merging, after addition then removal of a 1M file
     TEST8: --depth=1 fetching and merging, after addition of a 1M file
     TEST9: --depth=1 fetching and merging, after removal of a 1M file
-    TEST10: --depth=1 fetching and merging, after addition then removal of 1M a file"
+    TEST10: --depth=1 fetching and merging, after addition then removal of 1M a file
+    TEST17: --depth=1 fetching and merging, after addition of a 1M file in submodule
+    TEST18: --depth=1 fetching and merging, after removal of a 1M file in submodule
+    TEST19: --depth=1 fetching and merging, after addition then removal of a 1M file in submodule"
 }
 
 #USEFUL FUNCTIONS FOR THE TESTS
@@ -57,70 +60,87 @@ get_bandwidth(){
 }
 
 #TESTS ON THE INITIAL POPULATING OF THE REPO
+section "Tests on the initial populating of the repository"
 test0(){
     section TEST0
-    echo "TEST 0 : case of classic cloning."
+    echo "TEST 0: classic cloning."
     git clone --recurse-submodules --progress --no-local $1 &> cloning_text
     cd $REPO_NAME
     run git submodule update --init --recursive --force --remote --progress &> /dev/null
     cd ..
     get_storage_used "./$REPO_NAME" 
     get_bandwidth cloning_text
-    echo "memory usage in a classic cloning : $mem"
-    echo "bandwidth usage : $bw"    
+    echo "memory usage: $mem"
+    echo "bandwidth usage (submodule excluded): $bw"    
     run rm cloning_text
     run rm -rf $REPO_NAME 
 }
 
 test1(){
     section TEST1
-    echo "TEST 1 : case of --single-branch cloning."
+    echo "TEST 1: --single-branch cloning."
     git clone --recurse-submodules --progress --single-branch --no-local $1 &> cloning_text
     cd $REPO_NAME
     run git submodule update --init --recursive --force --remote --progress &> /dev/null
     cd ..
     get_storage_used ./$REPO_NAME
     get_bandwidth cloning_text
-    echo "memory usage in a --single-branch cloning : $mem"
-    echo "bandwidth usage : $bw"
+    echo "memory usage: $mem"
+    echo "bandwidth usage (submodule excluded): $bw"
     run rm cloning_text
     run rm -rf $REPO_NAME
 }
 
 test2(){
     section TEST2
-    echo "TEST 2 : case of --depth=1 --no-single-branch"
+    echo "TEST 2: --depth=1 --no-single-branch"
     git clone --recurse-submodules --progress --depth=1 --no-local --no-single-branch $1 &> cloning_text
     cd $REPO_NAME
     run git submodule update --init --recursive --force --remote --progress --depth=1 --no-single-branch &> /dev/null
     cd ..
     get_storage_used ./$REPO_NAME
     get_bandwidth cloning_text
-    echo "memory usage in a --depth=1 --no-single-branch cloning : $mem"
-    echo "bandwidth usage : $bw"
+    echo "memory usage: $mem"
+    echo "bandwidth usage (submodule excluded): $bw"
     run rm cloning_text
     run rm -rf $REPO_NAME
 }
 
 test3(){
     section TEST3
-    echo "TEST 3 : case of --depth=1 with single-branch (default))"
+    echo "TEST 3: --depth=1 with single-branch (default))"
     git clone --recurse-submodules --recurse-submodules --progress --single-branch --no-local --depth=1 $1 &> cloning_text
     cd $REPO_NAME
     run git submodule update --init --recursive --force --remote --progress --depth=1 &> /dev/null
     cd ..
     get_storage_used ./$REPO_NAME
     get_bandwidth cloning_text
-    echo "memory usage in a --depth=1 with single-branch cloning : $mem"
-    echo "bandwidth usage : $bw"
+    echo "memory usage: $mem"
+    echo "bandwidth usage (submodule excluded): $bw"
     run rm cloning_text
     run rm -rf $REPO_NAME
 }
 
 test4(){
     section TEST4
+    echo "TEST 4: --depth=1 with single-branch (default) and reflog and gc"
+    git clone --recurse-submodules --recurse-submodules --progress --single-branch --no-local --depth=1 $1 &> cloning_text
+    cd $REPO_NAME
+    run git submodule update --init --recursive --force --remote --progress --depth=1 &> /dev/null
+    git reset --hard
+    cd ..
+    get_storage_used ./$REPO_NAME
+    get_bandwidth cloning_text
+    echo "memory usage: $mem"
+    echo "bandwidth usage (submodule excluded): $bw"
+    run rm cloning_text
+    run rm -rf $REPO_NAME
+}
+
+test5(){
+    section TEST5
     run mkdir $REPO_NAME
-    run echo "TEST 4 : case of sparse-checking only $FILES_TO_KEEP with depth=1"
+    run echo "TEST 5 : sparse-checking only $FILES_TO_KEEP with depth=1"
     #creating a git repo with sparse-checking settings
     run cd $REPO_NAME
     run git init -q
@@ -133,16 +153,16 @@ test4(){
     git checkout -f origin/main &> /dev/null
     get_storage_used .
     echo "memory usage: $mem"
-    echo "bandwidth usage : unknown"
+    echo "bandwidth usage (submodule excluded): unknown"
     cd ..
     run rm -rf $REPO_NAME
 }
 
-
-#TESTS ON THE UPDATING OF THE REPOSITORY
-test5(){
-    section TEST5
-    run echo 'TEST 5 : case of classic fetching and merging, after addition of a 1M file'
+#Tests on the updating of the repository
+#classic fetching
+test6(){
+    section TEST6
+    run echo 'TEST 6: after addition of a 1M file'
     #initialization
     git clone --recurse-submodules --progress --no-local $1 &> /dev/null
     cd $REPO_NAME
@@ -168,10 +188,9 @@ test5(){
     cd ../..
     rm -rf performance_testing
 }
-
-test6(){
-    section TEST6
-    run echo 'TEST 6 : case of classic fetching and merging, after removal of a 1M file'
+test7(){
+    section TEST7
+    run echo 'TEST 7: after removal of a 1M file'
     #initialization
     git clone --recurse-submodules --progress --no-local $1 &> /dev/null
     cd $REPO_NAME
@@ -197,10 +216,9 @@ test6(){
     cd ../..
     rm -rf performance_testing
 }
-
-test7(){
-    section TEST7
-    run echo 'TEST 7 : case of classic fetching and merging, after addition then removal of a 1M file'
+test8(){
+    section TEST8
+    run echo 'TEST 8: after addition then removal of a 1M file'
     #initialization
     git clone --recurse-submodules --progress --no-local $1 &> /dev/null
     cd $REPO_NAME
@@ -229,9 +247,10 @@ test7(){
     rm -rf performance_testing
 }
 
-test8(){
-    section TEST8
-    run echo 'TEST 8 : case of fetching --depth=1 and merging, after addition of a 1M file'
+#fetching with --depth=1
+test9(){
+    section TEST9
+    run echo 'TEST 9: after addition of a 1M file'
     #initialization
     git clone --recurse-submodules --progress --no-local $1 &> /dev/null
     cd $REPO_NAME
@@ -256,10 +275,9 @@ test8(){
     cd ../..
     rm -rf performance_testing
 }
-
-test9(){
-    section TEST9
-    run echo 'TEST 9 : case of --depth=1 fetching and merging, after removal of a 1M file'
+test10(){
+    section TEST10
+    run echo 'TEST 10: after removal of a 1M file'
     #initialization 
     git clone --recurse-submodules --progress --no-local $1 &> /dev/null
     cd $REPO_NAME
@@ -268,12 +286,12 @@ test9(){
     #modification of the remote repo  
     cd ../$REMOTE
     run rm sample0
-    run git add sample0 
+    run git add sample0
     run git commit --quiet -m"1M sample0 deleted"
     cd ../../$REPO_NAME
     #fetching
     run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
-    run git fetch --progress --tags --depth=1 origin &> /dev/null
+    git fetch --progress --tags --prune --depth=1 origin &> /dev/null
     git checkout -f origin/main &> /dev/null
     get_storage_used .
     mem_after=$mem
@@ -284,10 +302,9 @@ test9(){
     cd ../..
     rm -rf performance_testing
 }
-
-test10(){
-    section TEST10
-    run echo 'TEST 10 : case of --depth=1 fetching and merging, after addition then removal of a 1M file'
+test11(){
+    section TEST11
+    run echo 'TEST 11: after addition then removal of a 1M file'
     git clone --recurse-submodules --progress --no-local $1 &> /dev/null
     cd $REPO_NAME
     get_storage_used .
@@ -315,9 +332,274 @@ test10(){
     rm -rf performance_testing
 }
 
-test11(){
-    section TEST11
-    run echo 'TEST 11 : case of --depth=1 fetching and merging, after addition of a 1M file in submodule'
+# --depth=1 fetching with reflog and gc
+test12(){
+    section TEST12
+    run echo 'TEST 12: after addition of a 1M file'
+    #initialization
+    git clone --recurse-submodules --progress --no-local $1 &> /dev/null
+    cd $REPO_NAME
+    echo "un truc écrit en plus" >> untexte
+    get_storage_used .
+    mem_before=$mem
+    #modification of the remote repo  
+    cd ../$REMOTE
+    create_random_file 'sample5' '1M' #adding a 1M file
+    run git add sample5 
+    run git commit --quiet -m"fourth 1M sample created"
+    cd ../../$REPO_NAME
+    run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
+    run git fetch --progress --tags --depth=1 origin &> /dev/null
+    git checkout -f origin/main &> /dev/null
+    git reflog expire --expire=now --all &> /dev/null
+    git gc --aggressive --prune=now &> /dev/null
+    get_storage_used .
+    mem_after=$mem
+    mem=$(($mem_after-$mem_before))
+    echo "memory usage: +$mem"
+    cd ../$REMOTE
+    git reset --hard -q HEAD~1 
+    cd ../..
+    rm -rf performance_testing
+}
+test13(){
+    section TEST13
+    run echo 'TEST 13: after removal of a 1M file'
+    #initialization 
+    git clone --recurse-submodules --progress --no-local $1 &> /dev/null
+    cd $REPO_NAME
+    get_storage_used .
+    mem_before=$mem
+    #modification of the remote repo  
+    cd ../$REMOTE
+    run rm sample0
+    run git add sample0
+    run git commit --quiet -m"1M sample0 deleted"
+    cd ../../$REPO_NAME
+    #fetching
+    run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
+    git fetch --progress --tags --prune --depth=1 origin &> /dev/null
+    git checkout -f origin/main &> /dev/null
+    git reflog expire --expire=now --all &> /dev/null
+    git gc --aggressive --prune=now &> /dev/null
+    get_storage_used .
+    mem_after=$mem
+    mem=$(($mem_after-$mem_before))
+    echo "memory usage: $mem"
+    cd ../$REMOTE
+    git reset --hard -q HEAD~1
+    cd ../..
+    rm -rf performance_testing
+}
+test14(){
+    section TEST14
+    run echo 'TEST 14: after addition then removal of a 1M file'
+    git clone --recurse-submodules --progress --no-local $1 &> /dev/null
+    cd $REPO_NAME
+    get_storage_used .
+    mem_before=$mem
+    #modification of the remote repo  
+    cd ../$REMOTE
+    create_random_file 'sample5' '1M' #adding a 1M file
+    run git add sample5 
+    run git commit --quiet -m"fourth 1M sample created"
+    run rm sample5
+    run git add sample5
+    run git commit --quiet -m"1M "sample5" deleted"
+    cd ../../$REPO_NAME
+    #fetching
+    run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
+    run git fetch --progress --tags --depth=1 origin &> /dev/null
+    git checkout -f origin/main &> /dev/null
+    git reflog expire --expire=now --all &> /dev/null
+    git gc --aggressive --prune=now &> /dev/null
+    get_storage_used .
+    mem_after=$mem
+    mem=$(($mem_after-$mem_before))
+    echo "memory usage: $mem"
+    cd ../$REMOTE
+    git reset --hard -q HEAD~2
+    cd ../..
+    rm -rf performance_testing
+}
+
+#--depth=1 fetching with reset --hard
+test15(){
+    section TEST15
+    run echo 'TEST 15: after addition of a 1M file'
+    #initialization
+    git clone --recurse-submodules --progress --no-local $1 &> /dev/null
+    cd $REPO_NAME
+    echo "un truc écrit en plus" >> untexte
+    get_storage_used .
+    mem_before=$mem
+    #modification of the remote repo  
+    cd ../$REMOTE
+    create_random_file 'sample5' '1M' #adding a 1M file
+    run git add sample5 
+    run git commit --quiet -m"fourth 1M sample created"
+    cd ../../$REPO_NAME
+    run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
+    run git fetch --progress --tags --depth=1 origin &> /dev/null
+    git reset --hard origin/main &> /dev/null
+    get_storage_used .
+    mem_after=$mem
+    mem=$(($mem_after-$mem_before))
+    echo "memory usage: +$mem"
+    cd ../$REMOTE
+    git reset --hard -q HEAD~1 
+    cd ../..
+    rm -rf performance_testing
+}
+test16(){
+    section TEST16
+    run echo 'TEST 16: after removal of a 1M file'
+    #initialization 
+    git clone --recurse-submodules --progress --no-local $1 &> /dev/null
+    cd $REPO_NAME
+    get_storage_used .
+    mem_before=$mem
+    #modification of the remote repo  
+    cd ../$REMOTE
+    run rm sample0
+    run git add sample0
+    run git commit --quiet -m"1M sample0 deleted"
+    cd ../../$REPO_NAME
+    #fetching
+    run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
+    git fetch --progress --tags --prune --depth=1 origin &> /dev/null
+    git reset --hard origin/main &> /dev/null
+    get_storage_used .
+    mem_after=$mem
+    mem=$(($mem_after-$mem_before))
+    echo "memory usage: $mem"
+    cd ../$REMOTE
+    git reset --hard -q HEAD~1
+    cd ../..
+    rm -rf performance_testing
+}
+test17(){
+    section TEST17
+    run echo 'TEST 17: after addition then removal of a 1M file'
+    git clone --recurse-submodules --progress --no-local $1 &> /dev/null
+    cd $REPO_NAME
+    get_storage_used .
+    mem_before=$mem
+    #modification of the remote repo  
+    cd ../$REMOTE
+    create_random_file 'sample5' '1M' #adding a 1M file
+    run git add sample5 
+    run git commit --quiet -m"fourth 1M sample created"
+    run rm sample5
+    run git add sample5
+    run git commit --quiet -m"1M "sample5" deleted"
+    cd ../../$REPO_NAME
+    #fetching
+    run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
+    run git fetch --progress --tags --depth=1 origin &> /dev/null
+    git reset --hard origin/main &> /dev/null
+    get_storage_used .
+    mem_after=$mem
+    mem=$(($mem_after-$mem_before))
+    echo "memory usage: $mem"
+    cd ../$REMOTE
+    git reset --hard -q HEAD~2
+    cd ../..
+    rm -rf performance_testing
+}
+#--depth=1 fetching with reset --hard and reflog and gc
+test18(){
+    section TEST18
+    run echo 'TEST 18: after addition of a 1M file'
+    git clone --recurse-submodules --progress --no-local $1 &> /dev/null
+    cd $REPO_NAME
+    get_storage_used .
+    mem_before=$mem
+    #modification of the remote repo  
+    cd ../$REMOTE
+    create_random_file 'sample5' '1M' #adding a 1M file
+    run git add sample5 
+    run git commit --quiet -m"fourth 1M sample created"
+    cd ../../$REPO_NAME
+    #fetching
+    run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
+    run git fetch --progress --tags --depth=1 origin &> /dev/null
+    git reset --hard origin/main &> /dev/null
+    git reflog expire --expire=now --all &> /dev/null
+    git gc --aggressive --prune=now &> /dev/null
+    get_storage_used .
+    mem_after=$mem
+    mem=$(($mem_after-$mem_before))
+    echo "memory usage: $mem"
+    cd ../$REMOTE
+    git reset --hard -q HEAD~1
+    cd ../..
+    rm -rf performance_testing
+}
+test19(){
+    section TEST19
+    run echo 'TEST 19: after removal of a 1M file'
+    #initialization 
+    git clone --recurse-submodules --progress --no-local $1 &> /dev/null
+    cd $REPO_NAME
+    get_storage_used .
+    mem_before=$mem
+    #modification of the remote repo  
+    cd ../$REMOTE
+    run rm sample0
+    run git add sample0
+    run git commit --quiet -m"1M sample0 deleted"
+    cd ../../$REPO_NAME
+    #fetching
+    run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
+    git fetch --progress --tags --prune --depth=1 origin &> /dev/null
+    git reset --hard origin/main &> /dev/null
+    git reflog expire --expire=now --all &> /dev/null
+    git gc --aggressive --prune=now &> /dev/null
+    get_storage_used .
+    mem_after=$mem
+    mem=$(($mem_after-$mem_before))
+    echo "memory usage: $mem"
+    cd ../$REMOTE
+    git reset --hard -q HEAD~1
+    cd ../..
+    rm -rf performance_testing
+}
+test20(){
+    section TEST20
+    run echo 'TEST 20: after addition then removal of a 1M file'
+    git clone --recurse-submodules --progress --no-local $1 &> /dev/null
+    cd $REPO_NAME
+    get_storage_used .
+    mem_before=$mem
+    #modification of the remote repo  
+    cd ../$REMOTE
+    create_random_file 'sample5' '1M' #adding a 1M file
+    run git add sample5 
+    run git commit --quiet -m"fourth 1M sample created"
+    run rm sample5
+    run git add sample5
+    run git commit --quiet -m"1M "sample5" deleted"
+    cd ../../$REPO_NAME
+    #fetching
+    run git submodule update --init --recursive --force --depth=1 --remote &> /dev/null
+    run git fetch --progress --tags --depth=1 origin &> /dev/null
+    git reset --hard origin/main &> /dev/null
+    git reflog expire --expire=now --all &> /dev/null
+    git gc --aggressive --prune=now &> /dev/null
+    get_storage_used .
+    mem_after=$mem
+    mem=$(($mem_after-$mem_before))
+    echo "memory usage: $mem"
+    cd ../$REMOTE
+    git reset --hard -q HEAD~2
+    cd ../..
+    rm -rf performance_testing
+}
+#--depth=1 fetching after modification applied in submodule
+test21(){
+    section TEST21
+    run echo 'TEST 21: after addition of a 1M file'
     if [ "$WITH_SUBMODULE" = "true" ]; then
     git clone --recurse-submodules --progress --no-local $1 &> /dev/null
         cd $REPO_NAME
@@ -347,9 +629,9 @@ test11(){
     fi
 }
 
-test12(){
-    section TEST12
-    run echo 'TEST 12 : case of --depth=1 fetching and merging, after removal of a 1M file in submodule'
+test22(){
+    section TEST22
+    run echo 'TEST 22: after removal of a 1M file'
     if [ "$WITH_SUBMODULE" = "true" ]; then
         git clone --recurse-submodules --progress --no-local $1 &> /dev/null
         cd $REPO_NAME
@@ -379,9 +661,9 @@ test12(){
     fi
 }
 
-test13(){
-    section TEST13
-    run echo 'TEST 13 : case of --depth=1 fetching and merging, after addition then removal of a 1M file in submodule'
+test23(){
+    section TEST23
+    run echo 'TEST 23: after addition then removal of a 1M file'
     if [ "$WITH_SUBMODULE" = "true" ]; then
         git clone --recurse-submodules --progress --no-local $1 &> /dev/null
         cd $REPO_NAME
@@ -436,15 +718,31 @@ if [ "$ALL_TESTS" = "true" ]; then
     test3 $REMOTE
     test4 $REMOTE
     test5 $REMOTE
+    echo $(section "Tests on the updating of the repository")
+    section "classic fetching"
     test6 $REMOTE
     test7 $REMOTE
     test8 $REMOTE
+    echo $(section "fetching with --depth=1")
     test9 $REMOTE
     test10 $REMOTE
     test11 $REMOTE
+    echo $(section "--depth=1 fetching with reflog and gc")
     test12 $REMOTE
     test13 $REMOTE
-
+    test14 $REMOTE
+    echo $(section "--depth=1 fetching with reset --hard")
+    test15 $REMOTE
+    test16 $REMOTE
+    test17 $REMOTE
+    echo $(section "--depth=1 fetching with reset --hard and reflog and gc")
+    test18 $REMOTE
+    test19 $REMOTE
+    test20 $REMOTE
+    echo $(section "--depth=1 fetching after modification applied in submodule")
+    test21 $REMOTE
+    test22 $REMOTE
+    test23 $REMOTE
 
 elif [ -n "$TEST_NUM" ]; then
     case $TEST_NUM in
@@ -476,6 +774,8 @@ elif [ -n "$TEST_NUM" ]; then
             test12 $REMOTE;;
         13)     
             test13 $REMOTE;;
+        21)
+            test21 $REMOTE;;
         *)
             echo "Error: Invalid test number"
             die;;