Which cache is safe to delete/improves boot time?

[HarryWarden]

I recall reading that deleting one of the caches (the system cache or the cache found in the username folder) will speed up boot time while the other one will slow it down because the computer has to rebuild the cache at startup but I can't remember which is which.

 

[justperry]

I recall reading that deleting one of the caches (the system cache or the cache found in the username folder) will speed up boot time while the other one will slow it down because the computer has to rebuild the cache at startup but I can't remember which is which.

The are quite a few Caches.

/Library/Caches
/System/Library/Caches
/User/Username/Library/Caches

And also /Private/Var/Folders/XX if I am correct.

Lots of them are safe to delete, I think the ones in
/Library/Caches
/System/Library/Caches
are the ones which the system uses, they get rebuild after you delete them so the first start it will be a bit slower, but only on the first start.
Thereafter they won't rebuild, you could try if it makes a difference but I doubt it.
Rebuilding the System with Diskwarrior will probably make a difference though.