One example that will show another flavor of the point Peter makes (short, fast interrupts - process the rest elsewhere).
I had a project where some very complicated processing of serial data had to take priority over the "main" processing because fast responses to input were required. At the same time this could not interfere with interrupt response time.
With T2 interrupt set a the lowest priority level, and the remaining interrupts at high priority, I received the characters in the serial ISR, buffered it and then set TF2. Using the timer 2 interrupt routine for the remaining (long) processing of the data took care of the problem.
This, of course, makes T2 unusable for other things.

Just another way to keep critical interrupts short and sweet.

Have fun,

Erik