I have. Unfortunately, I run my screen at a scaled resolution, so Firefox routinely pegs a full core redrawing itself, and burns my battery like it was punctured.
Until that's fixed, I can't use it as my primary browser. This saddens me, because I otherwise love it.
EDIT: This is actually more reason for me to switch back to Linux; FF doesn't have this bug there.
Something like this came up the other day. Perhaps setting "gfx.compositor.glcontext.opaque" to true in about:config as suggested by pcwalton might help you until this bug is properly fixed?
It seems to have mitigated the issue some, but it hasn't eliminated it. I had somehow inferred from the web of related issues in the FF bug tracker that I'd need to use a nightly build for this to be effective.
Until that's fixed, I can't use it as my primary browser. This saddens me, because I otherwise love it.
EDIT: This is actually more reason for me to switch back to Linux; FF doesn't have this bug there.