I just got a new website built which is a Gantry template. I got some error, e.g. Fatal error: Out of memory. That is from Gantry's CSS LESS compiler. I tried to comment out the codes to by-pass compiler. It does not 100% work. Finally, I put a request to web host for increasing the buffer to 128MB. Then all works fine.

(Note that, I know you can use define function in php to increase your memory buffer, but some web hosts will not allow it.)