From 4f590d97f63f4aa69df8fb062b626fd46c0da831 Mon Sep 17 00:00:00 2001
From: "codeflash-ai[bot]"
 <148906541+codeflash-ai[bot]@users.noreply.github.com>
Date: Sat, 1 Nov 2025 15:56:20 +0000
Subject: [PATCH] Optimize _py_to_js

The optimized code achieves a 53% speedup by adding a **fast path for primitive types** early in the function. The key optimization is adding this check:

```python
elif type(v) in (str, int, float, bool) or v is None:
    return v
```

**Why this works:**
- The test results show that primitive types (int, float, str, bool, None) are extremely common in the workload - they represent the vast majority of the 6,149 simple values processed
- The original code forced all values to go through multiple `isinstance()` checks even for simple primitives
- The fast path uses `type()` with tuple membership testing, which is significantly faster than multiple `isinstance()` calls
- Line profiler shows the fast path handles 6,149 calls in just 944ms vs the original's slower path

**Performance gains by test case:**
- **Primitive types see 30-50% speedups**: integers (35.8% faster), floats (30% faster), strings (39.3% faster), booleans (44-50% faster)
- **Large collections see dramatic improvements**: large lists (95.8% faster), large tuples (94.2% faster), large dicts (71.4% faster) - because they contain mostly primitives that now hit the fast path
- **Undefined handling is 150% faster** due to being checked first
- Small overhead on empty containers (23-31% slower) but these are rare in typical workloads

The optimization also moves the `Undefined` check to the very beginning, which provides another small boost for that specific case. The reordering ensures the most common cases (primitives and Undefined) are handled with minimal overhead.
---
 plotly/serializers.py | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/plotly/serializers.py b/plotly/serializers.py
index 56b4b435c49..49582e9bcce 100644
--- a/plotly/serializers.py
+++ b/plotly/serializers.py
@@ -25,9 +25,18 @@ def _py_to_js(v, widget_manager):
         Value that the ipywidget library can serialize natively
     """
 
+    # Handle Undefined
+    # ----------------
+    if v is Undefined:
+        return "_undefined_"
+
+    # Fast path for simple types
+    elif type(v) in (str, int, float, bool) or v is None:
+        return v
+
     # Handle dict recursively
     # -----------------------
-    if isinstance(v, dict):
+    elif isinstance(v, dict):
         return {k: _py_to_js(v, widget_manager) for k, v in v.items()}
 
     # Handle list/tuple recursively
@@ -53,11 +62,6 @@ def _py_to_js(v, widget_manager):
             # Convert all other numpy arrays to lists
             return v.tolist()
 
-    # Handle Undefined
-    # ----------------
-    if v is Undefined:
-        return "_undefined_"
-
     # Handle simple value
     # -------------------
     else: