The performance improvement going to Haswell is < 10%. Also, I feel you've been fooled by marketing gimmicks. Video decoding is lossless. You get exactly the bits that were in the compressed video file. There are some minor optimisations to be made here and there but anything that consumes 100% CPU is broken. Modern CPU usage should never exceed 5% for decoding Blu-ray video even in software. Even after applying questionable post processing filters that subjectively improve the video you should be no where close to 100%. You'll gain absolutely nothing by upgrading your CPU before 8k video.
If there's a bug with hardware video decoding, then disable hardware decoding and use software. Hardware may have bugs (and may not be lossess), but software is flawless.
Last edited by KurianOfBorg; 01-04-2015 at 10:15 PM.