unpatch: slow loading of remote sessions

[reduzent]

On macOS and Windows, syncing from a peer can take quite some amount of time - up to a few minutes, depending on the size of the session, the number of instruments and effects used in the session, respectively. The issue is less pronounced on Linux, it seems.

[reduzent]

It looks like the repeated computation of the DSP graph takes a lot of CPU time. When turning DSP off during session loading, the loading time is significantly shortened.

[reduzent]

BTW: Loading is only slow when joining an already running session. Unpatch loads all instruments within one DSP-off-on cycle, but each of the instruments may cause further DSP-off-on cycles, which take more time the more stuff is loaded.

When loading a preset, DSP is until all is loaded and thus loading from preset takes significantly less time.