Hi
For RE2000, you should only be concerned with routing table size. For forwarding, it depends on type of line cards you are using.
RE2000 has 4G of memory running 32bit rpd. I think it has 2G max for rpd. It should be capable running of a few copies internet tables comfortably, let's say 2-3
However if you'd like to know the exact limit and your expectation is higher than what I mentioned above, I'd suggest to work with your account team/system engineer