diff --git a/codeflash/languages/javascript/mocha_runner.py b/codeflash/languages/javascript/mocha_runner.py
index 0dd385050..59d9c1043 100644
--- a/codeflash/languages/javascript/mocha_runner.py
+++ b/codeflash/languages/javascript/mocha_runner.py
@@ -185,14 +185,25 @@ def _extract_mocha_json(stdout: str) -> str | None:
             pass
 
     # Find the outermost JSON object containing "stats"
+    # Use find() to jump between braces instead of checking every character
     depth = 0
     start = None
-    for i, ch in enumerate(stdout):
-        if ch == "{":
+    pos = 0
+    while True:
+        next_open = stdout.find("{", pos)
+        next_close = stdout.find("}", pos)
+
+        if next_open == -1 and next_close == -1:
+            break
+
+        if next_open != -1 and (next_close == -1 or next_open < next_close):
+            i = next_open
             if depth == 0:
                 start = i
             depth += 1
-        elif ch == "}":
+            pos = i + 1
+        else:
+            i = next_close
             depth -= 1
             if depth == 0 and start is not None:
                 candidate = stdout[start : i + 1]
@@ -203,19 +214,72 @@ def _extract_mocha_json(stdout: str) -> str | None:
                     except json.JSONDecodeError:
                         pass
                 start = None
+            pos = i + 1
 
     return None
 
 
-def _build_mocha_command(
-    test_files: list[Path], timeout: int | None = None, default_timeout_ms: int = 60000
+def _build_mocha_behavioral_command(
+    test_files: list[Path], timeout: int | None = None, project_root: Path | None = None
+) -> list[str]:
+    """Build Mocha command for behavioral tests.
+
+    Args:
+        test_files: List of test files to run.
+        timeout: Optional timeout in seconds (converted to ms for Mocha).
+        project_root: Project root directory.
+
+    Returns:
+        Command list for subprocess execution.
+
+    """
+    cmd = ["npx", "mocha", "--reporter", "json", "--jobs", "1", "--exit"]
+
+    if timeout:
+        cmd.extend(["--timeout", str(timeout * 1000)])
+    else:
+        cmd.extend(["--timeout", "60000"])
+
+    cmd.extend(str(f.resolve()) for f in test_files)
+
+    return cmd
+
+
+def _build_mocha_benchmarking_command(
+    test_files: list[Path], timeout: int | None = None, project_root: Path | None = None
+) -> list[str]:
+    """Build Mocha command for benchmarking tests.
+
+    Args:
+        test_files: List of test files to run.
+        timeout: Optional timeout in seconds (converted to ms for Mocha).
+        project_root: Project root directory.
+
+    Returns:
+        Command list for subprocess execution.
+
+    """
+    cmd = ["npx", "mocha", "--reporter", "json", "--jobs", "1", "--exit"]
+
+    if timeout:
+        cmd.extend(["--timeout", str(timeout * 1000)])
+    else:
+        cmd.extend(["--timeout", "120000"])
+
+    cmd.extend(str(f.resolve()) for f in test_files)
+
+    return cmd
+
+
+def _build_mocha_line_profile_command(
+    test_files: list[Path], timeout: int | None = None, project_root: Path | None = None
 ) -> list[str]:
-    """Build a Mocha command.
+    """Build Mocha command for line profiling tests.
 
     Args:
         test_files: List of test files to run.
         timeout: Optional timeout in seconds (converted to ms for Mocha).
-        default_timeout_ms: Default timeout in milliseconds when timeout is not provided.
+        project_root: Project root directory.
 
     Returns:
         Command list for subprocess execution.
@@ -226,7 +290,7 @@ def _build_mocha_command(
     if timeout:
         cmd.extend(["--timeout", str(timeout * 1000)])
     else:
-        cmd.extend(["--timeout", str(default_timeout_ms)])
+        cmd.extend(["--timeout", "60000"])
 
     cmd.extend(str(f.resolve()) for f in test_files)
 
@@ -339,7 +403,7 @@ def run_mocha_behavioral_tests(
 
     _ensure_runtime_files(effective_cwd)
 
-    mocha_cmd = _build_mocha_command(test_files=test_files, timeout=timeout)
+    mocha_cmd = _build_mocha_behavioral_command(test_files=test_files, timeout=timeout, project_root=effective_cwd)
 
     mocha_env = test_env.copy()
     codeflash_sqlite_file = get_run_tmp_file(Path(f"test_return_values_{candidate_index}.sqlite"))
@@ -423,7 +487,7 @@ def run_mocha_benchmarking_tests(
 
     _ensure_runtime_files(effective_cwd)
 
-    mocha_cmd = _build_mocha_command(test_files=test_files, timeout=timeout, default_timeout_ms=120000)
+    mocha_cmd = _build_mocha_benchmarking_command(test_files=test_files, timeout=timeout, project_root=effective_cwd)
 
     mocha_env = test_env.copy()
     codeflash_sqlite_file = get_run_tmp_file(Path("test_return_values_0.sqlite"))
@@ -511,7 +575,7 @@ def run_mocha_line_profile_tests(
 
     _ensure_runtime_files(effective_cwd)
 
-    mocha_cmd = _build_mocha_command(test_files=test_files, timeout=timeout)
+    mocha_cmd = _build_mocha_line_profile_command(test_files=test_files, timeout=timeout, project_root=effective_cwd)
 
     mocha_env = test_env.copy()
     codeflash_sqlite_file = get_run_tmp_file(Path("test_return_values_line_profile.sqlite"))