Daniel Sperl, developer of the Sparrow Framework, recently posted a performance comparison on the Apple Developer forum where Sparrow ran 2.5 times faster with MRC code than the version upgraded to ARC.
A curious finding though it seemed very far off from real world observations. Being a synthetic benchmark no less. I decided to do a similar test based on the same code comparing cocos2d v2 and v3.
Fortunately cocos2d-iphone v3 has made a similar switch from MRC (v2.1 and earlier) to ARC (v3 preview). Unfortunately the internals of cocos2d also changed to some extent, for example custom collection classes written in C were replaced by Core Foundation classes. I don’t have a full overview of the changes, but at least the renderer doesn’t seem to have changed in any significant way. Yet.
So while comparability is good, it’s not like Sparrow where truly the only changes made were converting the code from ARC back to MRC. Take the following benchmark results and comparisons with two grains of salt and pepper on the side.
ARC vs MRC
The original benchmark done with Sparrow has seen MRC perform 2.5 times better than ARC in a synthetic “draw as many sprites as possible until framerate has dropped consistently below 30 fps” test:
Or so goes the argument. Still.
I wish Apple would just pull the plug and completely remove MRC support from LLVM. I’m getting tired, annoyed and sometimes angry when I browse stackoverflow.com and frequently find MRC code samples containing one or more blatant memory management issues.
Before I rant any further, this article is about testing the performance difference of ARC vs MRC code. I provide some examples, and the updated performance measurement project I’ve used before for cocos2d performance analysis, and the results of the full run at the bottom. I also split it into both synthetic low-level tests and closer to real-world algorithms to prove not one but two points:
ARC is generally faster, and ARC can indeed be slower - but that’s no reason to dismiss it altogether.
Measuring & Comparing Objective-C ARC vs MRC performance
Without further ado, here are the results of the low-level MRC vs ARC performance tests, obtained from an iPod touch 5th generation with compiler optimizations enabled (release build): Continue reading »
