alt Hacker NewsFPGA speed is a common misconception. They often have run at quite modest frequencies, and come with limited memory capacity compared to a GPU at same price range.
Speed (clocks speed) , is dependent on your design layout, and for any resonably advanced layout, it takes lots of knowledge to push the clockspeed beyond 200Mhz on 'consumer'/prosumer models. (Compare to a few GHz for GPU/CPU).
FPGA speed shine where they can pipeline massively parallel calculations through pipelines with minimal lookups.
You can get 900 MHz designs on FPGAs, but yes you need very good engineers and patience to get that.
Yes SRAM is limited but that's more of a ram-process limitation than a limitation of FPGA