I'm not sure if this is the place to ask for such tips and tricks, but...
How do other users handle projects with lots of HD clips? Like for example all the material from one holiday, maybe 5 hours of HD raw material that you want to cut down to one hour? If I load 4 GB in 228 file into kdenlive at once, my system stays usable. Not bad, so far. I can use folders for the clips inside kdenlive so that I don't get too confused. The timeline, on the other hand, can't be segmented or structured, like in chapters for example. Daydream: "Minimize this chapter" in the timeline, or even "unload from RAM" without deleting it from the project. Speaking about RAM: I'm not sure how much kdenlive can load on my less than average hardware. I tried 6,6 GB in 465 files. No fun, kdenlive needs half an hour to load them. 9 GB of data in swap space. Playback (project or clip monitor) not in realtime anymore. Everything I try to do is very slow. I guess I won't try that again.