Editing Macintosh Toolbox (section)

== Performance Optimizations ==

=== Register-Based Calling Conventions ===
Critical routines bypass stack operations for speed:

'''QuickDraw Optimizations:'''
* '''Region operations''': Pass region handles in A0/A1
* '''Line drawing''': Coordinates in D0-D3
* '''Pattern fills''': Pattern pointer in A0

'''Memory Manager Fast Paths:'''
* '''NewPtr/NewHandle''': Size in D0, result in A0
* '''GetHandleSize''': Handle in A0, size in D0
* '''HandToHand''': Source in A0, dest in A0

=== Caching Mechanisms ===

'''Font Cache:'''
* '''512-byte bitmap cache''' per font
* '''Strike matrices''' for different sizes
* '''Width tables''' for kerning

'''Resource Map Cache:'''
* '''In-memory map''' for each open file
* '''Handle table''' for loaded resources
* '''One-deep cache''' for most recent

'''Menu Bar Cache:'''
* '''Pixel width calculations''' stored
* '''Menu item enables''' pre-computed
* '''Hierarchical menu''' locations cached