I can't think of many practical uses for this, so it probably isn't implemented, but I have an edge-case desire for it so I thought I'd ask.
Basically I'm creating a Torque animation in CartoDB of natural disaster data from FEMA. So it shows all the disaster declarations by month and county they were declared in. It runs and looks great in Chrome and even IE.
Surprisingly, though, it freezes up a lot for me in Firefox -- in particular around September 2005 when Katrina hit and disasters were declared in basically every county east of the Mississippi. Lots of simultaneous points grind it to a halt for several seconds on my test computer.
Playing around with the settings, I came to the conclusion I can fix it by changing the composite operations (how CartoDB visually blends overlapping geometry). The setting I find the best looking, "lighter," is apparently more graphically intensive than one like "source-over." Side-by-side comparison below the post.
I want to keep "lighter" for most browsers, and have it gracefully degrade to "source-over" for Firefox. Is this possible, or do I just have to suck it up and use source-over?