I got a workstation class machine for rendering video and I came to Kdenlive via Lightworks (which still isn't open source despite the promises made some years ago).

Anyway - even though Kdenlive is able to render my compositions to screen at almost full speed (with a bunch of effects on, but not a massive number) when I hit the render button, it seems like I've sent it to a Raspberry Pi. I'm running a naked test now (effects, just the H.264 video all clanked together on timeline - this is an 80 ish minute show so you can see that I need hardware accelerated render. Even the startup phase takes quite a while. If someone can point me to a log, I'll happily pop it here so someone in the know can have a look. I've set this one for H.264, lossless with 4 threads since that appears to be the maximum.

Obviously something is badly wrong either with my configuration or something somewhere but I'm utterly at a loss for what it could be. I've used the version from the Ubuntu PPA which isn't working too well (lack of requisite icons with me being on Mate 16.04) and the "Appimage" version which works rather beautifully.

I have 32 threads ready to rock an SSD and recent nVidia graphics card so it should be able to render at reasonable speed (comparable to other software in this area) but it's not even close. (For comparison, my 8-core 2008 Mac Pro was faster under After Effects doing similar work).

I suspect the problem lies in the MLT framework but if it can render to screen at 8-10 FPS (give or take) why is it sticking in the mud when it comes to render.

Coming from Lightworks was a breath of fresh air - it's just so "blech" compared to the other NLEs I've used: Kdenlive can teach it a thing or three in the usability stakes.

I'm in a pickle here - I guess I should have tested rendering speed first but I've become accustomed to the preview (RAM) renders being a good guide to what sort of performance to expect.