I haven't actually tested this. Perhaps someone else has who could chime in.
I would imagine it would be faster. If nobody chimes in who has tested it, you could test it and then come tell us.
The whole point of the caches is to make processing faster so that items don't need to be rerendered.
The only reason to clear the cache is if a bad result has been mistakenly cached.
Thank you both for your input, Szalam I'll certainly give it a go and report my findings...
Todd, so you're suggesting that really I should never clear the cache unless there is an error in there?
That's intriguing, I normally clear the cache after most sessions as I see it as good housekeeping. But I have plenty of disk space and a large cache, 200gb at the minute, so if I'm understanding you correctl then I should just let the cache fill up and auto wipe and that will speed up my render times?
I'll certainly give that a go from now on...I guess the only issue would be if I made use of Apple time machine, in which case my time machine drive would fill up pretty quickly with cached items. I guess I could tell time machine to ignore the cache folder...
Only clear your cache when you need to get the disk space back for some other purpose or when you are moving on to an entirely different set of work (or to clear out a bad cached item). Note that the disk cache persists across projects and can store cached items for commonly used assets. For example, if you always start from the same template or use the same graphics, you can get some speedup by keeping your disk cache around from one project to the next.
Brilliant, thanks for all your help guys.