diff --git a/codeflash/code_utils/time_utils.py b/codeflash/code_utils/time_utils.py
index 12afc6363..8b2625d15 100644
--- a/codeflash/code_utils/time_utils.py
+++ b/codeflash/code_utils/time_utils.py
@@ -7,58 +7,61 @@
 
 
 def humanize_runtime(time_in_ns: int) -> str:
-    runtime_human: str = str(time_in_ns)
+    runtime_human: str
     units = "nanoseconds"
     if 1 <= time_in_ns < 2:
         units = "nanosecond"
 
-    if time_in_ns / 1000 >= 1:
-        time_micro = float(time_in_ns) / 1000
-        
+    if time_in_ns >= 1_000:
         # Direct unit determination and formatting without external library
-        if time_micro < 1000:
-            runtime_human = f"{time_micro:.3g}"
-            units = "microseconds" if time_micro >= 2 else "microsecond"
-        elif time_micro < 1000000:
-            time_milli = time_micro / 1000
-            runtime_human = f"{time_milli:.3g}"
-            units = "milliseconds" if time_milli >= 2 else "millisecond"
-        elif time_micro < 60000000:
-            time_sec = time_micro / 1000000
-            runtime_human = f"{time_sec:.3g}"
-            units = "seconds" if time_sec >= 2 else "second"
-        elif time_micro < 3600000000:
-            time_min = time_micro / 60000000
-            runtime_human = f"{time_min:.3g}"
-            units = "minutes" if time_min >= 2 else "minute"
-        elif time_micro < 86400000000:
-            time_hour = time_micro / 3600000000
-            runtime_human = f"{time_hour:.3g}"
-            units = "hours" if time_hour >= 2 else "hour"
+        if time_in_ns < 1_000_000:
+            time_val = float(time_in_ns) / 1_000.0
+            runtime_human = f"{time_val:.3g}"
+            units = "microseconds" if time_val >= 2 else "microsecond"
+        elif time_in_ns < 1_000_000_000:
+            time_val = float(time_in_ns) / 1_000_000.0
+            runtime_human = f"{time_val:.3g}"
+            units = "milliseconds" if time_val >= 2 else "millisecond"
+        elif time_in_ns < 60_000_000_000:
+            time_val = float(time_in_ns) / 1_000_000_000.0
+            runtime_human = f"{time_val:.3g}"
+            units = "seconds" if time_val >= 2 else "second"
+        elif time_in_ns < 3_600_000_000_000:
+            time_val = float(time_in_ns) / 60_000_000_000.0
+            runtime_human = f"{time_val:.3g}"
+            units = "minutes" if time_val >= 2 else "minute"
+        elif time_in_ns < 86_400_000_000_000:
+            time_val = float(time_in_ns) / 3_600_000_000_000.0
+            runtime_human = f"{time_val:.3g}"
+            units = "hours" if time_val >= 2 else "hour"
         else:  # days
-            time_day = time_micro / 86400000000
-            runtime_human = f"{time_day:.3g}"
-            units = "days" if time_day >= 2 else "day"
-    
-    runtime_human_parts = str(runtime_human).split(".")
-    if len(runtime_human_parts[0]) == 1:
-        if runtime_human_parts[0] == "1" and len(runtime_human_parts) > 1:
+            time_val = float(time_in_ns) / 86_400_000_000_000.0
+            runtime_human = f"{time_val:.3g}"
+            units = "days" if time_val >= 2 else "day"
+    else:
+        runtime_human = str(time_in_ns)
+
+    # Use partition instead of split to avoid list allocation
+    head, sep, tail = runtime_human.partition(".")
+
+    # Reproduce original formatting rules exactly
+    if len(head) == 1:
+        if head == "1" and sep:
+            # original code appended 's' when integer part == "1" and there was a fractional part
             units = units + "s"
-        if len(runtime_human_parts) == 1:
-            runtime_human = f"{runtime_human_parts[0]}.00"
-        elif len(runtime_human_parts[1]) >= 2:
-            runtime_human = f"{runtime_human_parts[0]}.{runtime_human_parts[1][0:2]}"
+        if not sep:  # no fractional part
+            runtime_human = f"{head}.00"
+        elif len(tail) >= 2:
+            runtime_human = f"{head}.{tail[0:2]}"
         else:
-            runtime_human = (
-                f"{runtime_human_parts[0]}.{runtime_human_parts[1]}{'0' * (2 - len(runtime_human_parts[1]))}"
-            )
-    elif len(runtime_human_parts[0]) == 2:
-        if len(runtime_human_parts) > 1:
-            runtime_human = f"{runtime_human_parts[0]}.{runtime_human_parts[1][0]}"
+            runtime_human = f"{head}.{tail}{'0' * (2 - len(tail))}"
+    elif len(head) == 2:
+        if sep and tail:
+            runtime_human = f"{head}.{tail[0]}"
         else:
-            runtime_human = f"{runtime_human_parts[0]}.0"
+            runtime_human = f"{head}.0"
     else:
-        runtime_human = runtime_human_parts[0]
+        runtime_human = head
 
     return f"{runtime_human} {units}"