For the most part, the current version of AE doesn't use the GPU to make rendering faster except in one, outdated workflow; the ray-traced renderer. Are you using the ray-traced renderer? I'd recommend against it. Just use the standard renderer; it's faster. The ray-traced renderer is an obsolete way to create geometry in After Effects. There are much more powerful ways to do that now.
Details on how AE uses the GPU here: GPU (CUDA, OpenGL) features in After Effects
The more powerful workflow I mentioned announced here: CINEMA 4D Lite comes free with After Effects CC
Some training for Cineware and C4D Lite here: Cinema 4D Lite Reference [Video Tutorial Playlist] - Cineversity Training and Tools for Cinema 4D
That being said, you can tick the box to enable AE to use "unsupported" GPUs to accelerate the ray traced renderer in the settings, so you could try that.
When you say the preview is lagging, what do you mean? Do you mean when it's caching it's one frame per second (which could be normal or even great depending on what you've got in your comp)? Or do you mean after it's cached the preview it's playing the cached preview back slowly (which would indicate an issue)?
If you're new to AE, you could just be experiencing normal behavior and thinking it's wrong because you don't understand how AE works. After Effects is not a video editing program and it doesn't act like one. Instant playback is not a thing. Previews must be cached first.
If you're new to AE you should start here: Getting started with After Effects
Thank u very much for your answer.
I did try to tick the box of 'unsupported' GPU's, but there was no difference.
What I do not really understand, is, that AfterEffects seems to work faster with the Intel HD Graphics 520 (built into the screen of the surface book), than with the Nividia Geforce GPU (built into the keyboard of the surface book).
Yes the preview lags in caching. But a lot less with using the Intel instead of the Nvidia. And thats actually my problem :-/
I'd just like to use the advantage of the Nividia GPU and not settle with the Intel...
Any other idea?
Microsoft Surface Book (Intel Core i7-6600U, 16GB RAM, 512 GB SSD, Win 10 Pro)
After Effects CC 2015 (Creative Cloud)
That's...odd. What is in your composition?
Do you have the hardware accelerate panels turned on or off?
That template is just using the standard renderer, right?
How does it behave in AE CC 2014?
I didn't do any changes to hardware accelerate panels. So I guess it's the standard setting.
The templates use the standard renderer, yes.
It's exactly the same in AE CC 2014. I've tried that early on.
Could it be that it goes into a similar direction like the problems with Photoshop & AI?
--> Surface Book
Possibly. Did you try the suggestion in that thread for fixing it?
yes - I've tried them... Didn't help...
All I can suggest is contacting Adobe support and/or filing a bug report: Feature Request/Bug Report Form
I'm sure the AE team (who are the ones who get the bug reports) would find your issue interesting and something to work on.