Index: gc_core/py/lang_core/tests_core.py
==================================================================
--- gc_core/py/lang_core/tests_core.py
+++ gc_core/py/lang_core/tests_core.py
@@ -26,11 +26,11 @@
         print('{} : {}'.format(label, end - start))
         if hDst:
             hDst.write("{:<12.6}".format(end-start))
 
 
-def perf (sVersion, bMemo=False):
+def perf (sVersion, sResultFile=""):
     "performance tests"
     print("Performance tests")
     gc_engine.load()
     gc_engine.parse("Text to compile rules before launching real tests.")
 
@@ -38,11 +38,11 @@
     spfPerfTest = os.path.join(spHere, "perf.txt")
     if not os.path.exists(spfPerfTest):
         print(f"No file <perf.txt> in <{spHere}>")
         return
     with open(spfPerfTest, "r", encoding="utf-8") as hSrc:
-        hDst = open("./gc_lang/"+sLang+"/perf_memo.txt", "a", encoding="utf-8", newline="\n")  if bMemo  else None
+        hDst = open(sResultFile, "a", encoding="utf-8", newline="\n")  if sResultFile  else None
         if hDst:
             hDst.write("{:<12}{:<20}".format(sVersion, time.strftime("%Y.%m.%d %H:%M")))
         for sText in ( s.strip() for s in hSrc if not s.startswith("#") and s.strip() ):
             with timeblock(sText[:sText.find(".")], hDst):
                 gc_engine.parse(sText)

Index: make.py
==================================================================
--- make.py
+++ make.py
@@ -449,11 +449,12 @@
                 try:
                     tests = importlib.import_module(f"grammalecte.{sLang}.tests_core")
                 except ImportError:
                     print(f"# Error. Import failed: grammalecte.{sLang}.tests_core")
                 else:
-                    tests.perf(sVersion, xArgs.perf_memo)
+                    sResultFile = f"gc_lang/{sLang}/perf_memo.text"  if xArgs.perf_memo  else ""
+                    tests.perf(sVersion, sResultFile)
 
             # JavaScript linter
             if xArgs.lint_web_ext:
                 with helpers.CD("_build/webext/"+sLang):
                     os.system(r'web-ext lint -o text')