Denoising before or after resizing

DeGrainMedian is a pretty weak denoiser. If you want stronger denoising, try fft3dfilter/fft3dpu, or dfttest, or frfun, or mvdegrain. HQDN3D is a very fast filter and can do a decent job sometimes, too. I'd always do it before resizing, personally.

At the moment I'm using two different profiles: I'm looking for a good tradeoff in terms of encoding time Main: --pass 1 --progress --bitrate 500 --stats C:\ttt\input.stats --threads auto --subme 1 --analyse none --me dia --ref 1 --output NUL C:\ttt\input.avs --pass 2 --progress --bitrate 500 --stats C:\ttt\input.stats --threads auto --analyse p8x8,b8x8,i4x4,p4x4 --subme 6 --output C:\ttt\output.mp4 C:\ttt\input.avs High: --pass 1 --progress --bitrate 500 --stats C:\ttt\input.stats --threads auto --bframes 3 --b-pyramid --direct auto --filter 1:1 --subme 1 --analyse none --me dia --ref 1 --output NUL C:\ttt\input.avs --pass 2 --progress --bitrate 500 --stats C:\ttt\input.stats --threads auto --ref 16 --bframes 3 --b-pyramid --weightb --b-rdo --bime --direct auto --filter 1:1 --analyse all --8x8dct --no-fast-pskip --subme 7 --me umh --trellis 2 --mixed-refs --output C:\ttt\output.mp4 C:\ttt\input.avs and the avs DirectShowSource("C:/t1.mkv") BicubicResize(576, 320, 0, 0.5) ConvertToYV12()

Ok, and probably it doesn't improve a lot the quality. For the rest is possible to improve the sharpness of the resulting video?