Optimizations can take a long time. It is strange and cumbersome that the optimization routine in MC is modal, preventing the user from doing other things in that copy of MC. It should be non-modal, and run in the background, even if it needs to lock the chart like tradestation does (although even this shouldn't be necessary since the optimization can run off a copy of the chart made at optimization start). What if I wanted to view a workspace I had made changes to but not yet saved (therefore it can't be opened in another instance) while the optimization is ongoing?
Also, the user should be able to view the optimization results as each is completed in case he needs to change the parameters or is just curious.
Place a signal containing many parameters on a chart of a fairly large number of bars. Optimize several values on a basis that results in a large number of tests. That instance of MC is now unusable (except for the cancel button) until the optimization completes after some long period of time.