Hello, what version of the new client have you tried? Due to the issues regarding flash, older versions of the clients are becoming outdated, and will have issues. The newest version, 3.3, is more stable and more optimized than the previous version.

the 3.0 version of the miniclient was highly tasking on your computer, but the recent updated 3.3 version mitigates that issue. It is still worth a try, as it might help.