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Old 5th June 2014, 20:04   #535  |  Link
cyberbeing
Broadband Junkie
 
Join Date: Oct 2005
Posts: 1,859
I recently came across a sample which had poor performance with the old LV1 cache default of 256. Raising the the LV1 cache size to 2048 improved performance by 50% or so. That was just a single sample though, and I haven't come across any others which see a significant benefit over the old defaults (LV1 256, LV2 256, LV3 512, LV4 512).

On systems with slower CPUs and RAM, setting the caches larger than necessary will hurt overall performance slightly, since hashing and cache queries are not free when you are not generating any cache hits. You can think of the various cache sizes as the number of duplicate/repetitive entries for various elements of a script. In the future we may add a lookahead to make what gets cached more intelligent, but the way they are currently implemented, its possible for the caches to be filled with 'useless' dynamic data. This is why a hard limit on the number of entries is currently necessary.
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