I found a workaround for this problem: in driconf on Debugging page enable stub ARB_occlusion_query support on 915/945. This correspornds to ~/.drirc:
<option name="stub_occlusion_query" value="true" />
I hope this will help to find the bug (or if this is not a bug, please add this information to the README).
Note: disabling of texture tiling indeed improves performance on such card.