On NodeJS 4x, when configuring lru-cache with a max setting above 8192, behavior gradually becomes very slow. The longer it runs, the slower it gets.

• Test script: https://gist.github.com/aheckmann/6eefabd3c7a568451129
• Hardware: MacBook Pro, Processor 2 GHz Intel Core i7, Memory 8 GB 1600 MHz DDR3, Software OS X 10.9.5. Note: we observed this behavior in production on EC2 linux so it isn't limited to my MacBook

Starting with a max of 8193, the program abruptly slows down soon after the maximum number of elements have been reached. Soon it will take upwards of 30 seconds to process 5000 set/removes. As the max setting is raised higher and higher, performance still slows down but the program needs to run longer and longer to reach the same level of performance degradation.

I haven't been able to reproduce this behavior on any of these earlier releases of Node/iojs:

• iojs-3.3.1
• iojs-2.5.0
• iojs-1.8.4
• node-0.12.7
• node-0.11.16
• node-0.10.40

This is probably a V8 bug but worth making this known here.

Note: I forked this module and changed it to use Map instead of Object.create(null) and the issue is resolved. Not sure if switching to a Map is the right choice for this module due to backward compatibility (and browser support) but it looks like it could be a good solution going forward. I haven't pushed my code public yet but let me know if you'd be interested in going that direction.