I assume that you are running CPU- and GPU-WU. If so, it is probably the client running on the GPU which delays the working of Chrome.
In the BOINC-menu, select Tools, and there Computing preferences; in the "processor usage tab" un-tick "Use GPU while computer is in use". Save your values (OK) and try to run Chrome, if it works OK, problem solved: The GPU-WU takes much of the GPUs power and the rendering on the screen is severly hampered.
If you do not run GPU-WUs, and you have the problem, try to allocate less resources to BOINC: In the BOINC-settings select Tools, and there Computing preferences; Far down is the processor usage box, fill in e.g. 85% in the CPU-usage time and check if the problem is solved.
Good luck, YMMV.