[eluser]Jelmer[/eluser]
I doubt that would be a problem, but why in the world would you want to use 1000 rows on a single page? You'd paginate that query wouldn't you? And if you paginate it you can also cache it paginated.
Also: this isn't meant to replace your DB, your DB will always be more powerfull. It is meant to be used on queries that are needed often and are pretty simple. I expect there's a point where the time needed to retrieve the cache becomes more then the DB query would need, though I would not expect that point to be reached quickly. Your 1000 rows with multiple fields might just reach it (needing multiple megabytes)