Feature request: Speed Up CPU

[VladisM]

There is a lot of place to speed up CPU, ideal should be 50MHz or 100MHz. Just now CPU is running at 50MHz on Cyclone IV, and at 25MHz on low cost MAX10. Things that can be done to speed up:

• Pipeline CPU
• Add cache memory
• Replace FIFO in SDRAM driver with better domain crossing
• Don't close row in SDRAM
• Load next word from SDRAM into temp register when reading instruction