X Performance issue /w cubieboard 2: storage / mali / ??

[sappel]

Hello everyone,
I'm trying to get archlinux + lxde running from my cubieboards as thin clients (virt-viewer -> Proxmox Spice).
In general it works fine, but I have these tiny lags, the screen is flickering a bit and it just feels a little bit slow or laggy.

If I compare the remote performance with a x86 spice client, I can feel the difference - so server performance is fine, it has to be a client issue.

What can I do to verify a proper client setup? My guess is, the issue is has something to do with xorg drivers...
Are there any up 2 date tutorials to get the mali driver working (full hd, hdmi)?

Another idea is the speed of my storage (micro sd class 4 only), but does that affect the speed of X?

Thanks for any suggestions,
sappel