diff --git a/source/_extensions/controls_js_sim/__init__.py b/source/_extensions/controls_js_sim/__init__.py
index 477022b118..08ca7a79e4 100644
--- a/source/_extensions/controls_js_sim/__init__.py
+++ b/source/_extensions/controls_js_sim/__init__.py
@@ -1,9 +1,9 @@
 from pathlib import Path
 from typing import Any, Dict
 
-import os, glob
 from jsmin import jsmin
 from sphinx.application import Sphinx
+from sphinx.util import logging
 
 # Handle custom javascript
 # Groups, sorts, merges, and minifies the JS files associated with
@@ -25,74 +25,104 @@
     ".",
 ]
 
+LOGGER = logging.getLogger("controls_js_sim")
 
-def mergeAndMinify(out_folder):
-    if not os.path.isdir(out_folder):
-        os.makedirs(out_folder)
-
-    outputFile = os.path.join(out_folder, "pid-tune.js")
-
-    with open(outputFile, "w") as outf:
-        for folder in FOLDER_INCS:
-            jsRoot = os.path.dirname(__file__)
-            # find all js files in the specific folder
-            inFileNames = glob.glob(os.path.join(jsRoot, folder, "*.js"))
-
-            # sort file names alphabetically
-            # this allows a within-folder sort by number prefix if needed.
-            inFileNames.sort()
-
-            for inFileName in inFileNames:
-                with open(inFileName, "r") as inf:
-                    if not debugJS:
-                        # Minify each file independently - again, low bar solution for now
-                        minified = jsmin(inf.read())
-                        outf.write(minified)
-                        outf.write("\n")
-                    else:
-                        # Verbose, no minify, and add debug markers.
-                        outf.write("\n\n\n")
-                        outf.write(
-                            "//*******************************************************\n"
-                        )
-                        outf.write(
-                            "//*******************************************************\n"
-                        )
-                        outf.write("//**    {}\n".format(inFileName))
-                        outf.write(
-                            "//*******************************************************\n"
-                        )
-                        outf.write(
-                            "//*******************************************************\n"
-                        )
-                        outf.write("\n")
-                        outf.write(inf.read())
-                        outf.write("\n")
-
-    return outputFile
+STATIC_DIR = Path(__file__).parent / "_static"
+OUTPUT_FILE = STATIC_DIR / "pid-tune.js"
 
 
-def setup(app: Sphinx) -> Dict[str, Any]:
-    print("Generating and adding controls javascript...")
+def get_source_files():
+    """Get the list of source JavaScript files to be merged and minified."""
 
-    # Perform controls js setup
-    static_dir = Path(__file__).parent / "_static"
+    js_files = []
+    js_root = Path(__file__).parent
+
+    for folder in FOLDER_INCS:
+        # find all js files in the specific folder
+        folder_path = js_root / folder
+        # sort file names alphabetically
+        # this allows a within-folder sort by number prefix if needed.
+        in_file_names = sorted(folder_path.glob("*.js"))
+        js_files.extend(in_file_names)
+
+    return js_files
+
+
+def should_rebuild():
+    """Check if JavaScript needs to be rebuilt based on source file timestamps."""
+
+    # If output doesn't exist, must rebuild
+    if not OUTPUT_FILE.exists():
+        return True
+
+    output_mtime = OUTPUT_FILE.stat().st_mtime
+    source_files = get_source_files()
+
+    # Check if any source file is newer than output
+    for source_file in source_files:
+        if source_file.stat().st_mtime > output_mtime:
+            return True
+
+    return False
 
+
+def merge_and_minify():
+    """Merge and minify the JavaScript source files into a single output file."""
+
+    source_files = get_source_files()
+
+    with OUTPUT_FILE.open("w") as outf:
+        for source_file in source_files:
+            with source_file.open("r") as source:
+                if not debugJS:
+                    # Minify each file independently - again, low bar solution for now
+                    minified = jsmin(source.read())
+                    outf.write(minified)
+                    outf.write("\n")
+                else:
+                    # Verbose, no minify, and add debug markers.
+                    outf.write("\n\n\n")
+                    outf.write(
+                        "//*******************************************************\n"
+                    )
+                    outf.write(
+                        "//*******************************************************\n"
+                    )
+                    outf.write("//**    {}\n".format(source_file))
+                    outf.write(
+                        "//*******************************************************\n"
+                    )
+                    outf.write(
+                        "//*******************************************************\n"
+                    )
+                    outf.write("\n")
+                    outf.write(source.read())
+                    outf.write("\n")
+
+
+def generate_js_if_needed(app: Sphinx):
+    if should_rebuild():
+        LOGGER.info("Generating controls javascript...")
+        merge_and_minify()
+        LOGGER.info("Done.")
+    else:
+        LOGGER.debug("Controls javascript is up to date, skipping rebuild.")
+
+
+def setup(app: Sphinx) -> Dict[str, Any]:
+    # Perform controls js setup
     # everything written to this new static folder in this `setup` will be copied to the build static folder as is
     app.connect(
         "builder-inited",
-        (lambda app: app.config.html_static_path.append(static_dir.as_posix())),
+        (lambda app: app.config.html_static_path.append(STATIC_DIR.as_posix())),
     )
 
-    # Generate merged/minified PID tuning source
-    mergeAndMinify(static_dir)
+    app.connect("builder-inited", generate_js_if_needed)
 
     # Add interactive PID tuning
     app.add_js_file("pid-tune.js")
     app.add_css_file("pid-tune.css")
 
-    print("Done.")
-
     return {
         "parallel_read_safe": True,
         "parallel_write_safe": True,