Yes, it is slow. PC133 is "ancient". As I pointed out, even in 8 year old hardware it was trivial to get more than 6 times that performance out of a RAM disk device using filesystem benchmarking tools.
> If it is, then I wonder if you can parallelize to 4 slots for ~3.4GB/s
You probably can, but then you can't run code straight out of it, or read/write data directly as if it is normal RAM. Putting a filesystem on it, RAID'ed over multiple slots will likely work great (especially so since it's easy to get servers with a ton of DIMM slots, and it'll allow much better server density than trying to fit in more drive slots). But treating it as RAM will be slow.
> If it is, then I wonder if you can parallelize to 4 slots for ~3.4GB/s
You probably can, but then you can't run code straight out of it, or read/write data directly as if it is normal RAM. Putting a filesystem on it, RAID'ed over multiple slots will likely work great (especially so since it's easy to get servers with a ton of DIMM slots, and it'll allow much better server density than trying to fit in more drive slots). But treating it as RAM will be slow.