One big offscreen buffer or multiple small ones?

Offscreen bitmaps aren't universal solution for optimization!

dc is a form offscreen bitmap...

drawline(0,0,2,2) draws 3 pixels, drawing bitmaps 3x3 draws 9, so if battery depend on number of drawing pixels you don't save battery

No I''m using it to avoid all the expensive calculations I'm doing to draw all my datafields every second. So instead of doing all the calculations all the time, I only do them once and then just draw the offscreen buffer. But now I have just one big offscreenbuffer same size as screen where I draw everything to which I don't want all the calculations. But was wondering if I should draw them to individual smaller offscreen buffers or just one big offscreen buffer like how im doing now?

Can you attach a screenshot from your watch face? 

Basically every datafield i'm only updating on certain conditions. These updates costs a lot of cpu time, so i'm drawing them to an an offscreen buffer and I draw this offscreen buffer on the onupdate() and actually draw the datafields to the buffer only when needed. 

This does save a lot of battery usage, but I was wondering should I keep using 1 big offscreen buffer or should i make an smaller offscreen buffer for each datafield and draw those? I don't know if that would save any battery usage really, but was wondering. 

A lot of cpu comparing to what? Probably to your code... You forget about hardware, sensors etc. You can't see it in profiler.

But  I think you will spend days and won't save more battery, 0.2%/day (my watch face eats 0,2%/hour - f7/f6 without gps of course) is very good result, probably more takes hardware. 

I wonder, why don't you want to charge watch 7 times a year? Developer challenge, 60 days trip without sun (2x has solar).