Short answer is no. AE is not fully optimized because it calculates each frame one at a time and no single frame, unless there are literally hundreds and hundreds of layers or it is extremely big will use all of the computing power and memory of your system. Adobe is working on an complete overhaul so I would expect improvements in the future.
It is also strange that my card is not supported in AE with mercury, while in Premiere it is.
Playback of the same footage in Premiere is working very well btw.
> It is also strange that my card is not supported in AE with mercury
The "Mercury Playback Engine" has nothing to do with After Effects. That's just a marketing term for the performance improvements in Premiere Pro.
See this page for resources about making After Effects work faster: http://adobe.ly/eV2zE7
Could be a marketing term, but I would like to be able to use my GPU in After Effects, as I do in Premiere.
In my Premiere software I can easily playback my RAW sequence in real time. In AE however, it takes around a second to load each frame, even at quarter resolution.
If I take the RAW sequence from Pre and replace it with AE composition, then the playback in Pre gets even worse.
Also, I use CC version, so render multiple frames simultaneously (a setting used in the resources above) is no longer available.