VS Code has a pretty simple auto-complete mechanism for C - pretty much, it will auto-complete words that have been used before in the current file. That works for me, because I generally write APIs that have simple interfaces with a... I'm not sure how to describe it, parameter ordering that I expect.
If you're working with a bunch of libraries where function signature completion would be useful, then maybe a more functional IDE is useful. OpenGL is an example that comes to mind... I have no idea off the top of my head what the parameter ordering for glTexSubImage2D is. Generally though, I personally prefer the delay when occasionally having to look up an API over the delay caused by using a heavy IDE. On non-Windows, I'm an emacs guy. I've tried Emacs-win32 and it just feels like a UFO on Windows.
To answer your question, I personally do use VS Code on Windows, even when I'm working with crazy APIs like OpenGL. It subjectively feels faster to me than Visual Studio or Eclipse, although that might just be in my head.
The intellisense feature (or whatever the Eclipse folks has called it) on Eclipse is pretty good if is able to resolve its indexing paths correctly. This is not always possible.
I also want Eclipse to be a lot faster. I come from a vim background, and Eclipse feels glacier.
