PIC speed problems

[skimask]

It just seems like your way does a lot of unnecessary stuff. I can give it a go but it looks like a lot of processing that doesnt need to be done. Having said that, you know what your talking about and im new to this. Plus you say your code actually works and mine still doesnt

It really doesn't do a lot of extra/unnecessary anything. All it does (or rather would do) is, the interrupt's would handle the PWM'ing on the LEDs for you (you update them in the main loop as required) and would handle putting any serial data received into a buffer (you pull the buffer in the main loop to update the LEDs brightness levels in the main loop as required).
Really very simple...That file that I attached earlier has a whole LOAD of code in it for handling various modes for this, that and the other thing (sleep mode, flashing, fading, color 'phasing', etc.etc.)...a LOT of stuff you wouldn't even come close to needing for your setup.

I modified that file I was talking about...4 channels (RGBW)...
Change it up a bit to fit your PIC and hardware and try it out. No serial support, but it'll show you how the main loop can work PWM'ing with interrupts on the LEDs.
The LEDs MUST be on portA for this exact code to work right. If you split up the LEDs between different ports, they may flash a bit funny...