Welcome to the forum.

One of the nice things about PBP is ASM can be mixed in with it. Here is a perfect example
http://www.picbasic.co.uk/forum/showthread.php?t=3251
The above should take care of just about any interrupt timing issues you come across.

PBP has many commands that go back to BS1 (basic stamp) comparability and some of those do take up a little more code space and may take an extra cycle or so but no more so than poorly written ASM or C (IMHO).

In the end it is the person banging on the keyboard that makes the most difference.