I have a Ryzen-powered laptop with a hard-drive bottleneck. I have to link baloo_file to /usr/bin/true, or it freezes the desktop when it goes into I/O-Wait for disk reads. Only annoyance is whenever I update to the latest KDE5 release, baloo freezes everything, have to drop down into ctl-alt-f2, login as root and kill baloo, can't do it from the locked-up plasma desktop. But that is not why I dipped a feather into the inkwell.
I'll start Qt Creator or Gimp on a virtual desktop, then go check on a process in another desktop. When the application launched from another desktop finally paints its window, it does so on the current desktop, not the desktop in which it was launched. Can kdeinit notice the virtual desktop where the application menu launched it, then keep all of the application's startup windows over in that desktop instead of infesting a different desktop? May it's a bug, maybe it's a wishlist, I must be new, don't know where to voice such matters..

First of all, there is no such thing as KDE5.

You need to be a tad more detailed about your distribution and Plasma version, etc so we can narrow down what the problem is.

I don't know if there's much that can be done about this (besides maybe using kwin rules to assign the applications to specific desktops, or just being patient and letting the app create its window before switching desktops); but feel free to create a bug request to bugs.kde.org, as I would be interested in seeing if this issue could be fixed.