Thanks for your input! Pretty valuable. 
I started disliking Emacs lately even though I am using it ever since the beginning of 2002. It’s too slow. 
One thing I could never like about VIM is that it has to run in a console – but I hear this is no longer the case.
Could you recommend a full-blown GUI for VIM? I am open to giving it a fair try (read: several weeks or even months working in parallel with Emacs). I really am sick and tired of slow tools and I’d love to move to something snappier. And I hear VIM is better in this regard.
(BTW, the OCaml VIM scripts are insanely slow as well. They add something like 3 seconds lag on a server-grade CPU with 10 cores / 20 threads. I suspect the slowdown is not from a CPU load but slowness in following symlinks or, some I/O bottleneck in general. But never pursued it.)