Thank you for your reply.
In similar cases, reorganising the termbase helps. Do you experience the slowness with one particular termbase, or is it more of a general issue?
If it is a general issue, please try disabling LookAhead (Options > Editor > Automation), it should speed Studio up.
If it is related to one termbase in particular, please try to reorganise it in MultiTerm.
Please let me know if the above helped.