I don't like any of the answers offered. The one I think comes nearest to being sensible is to increase the test DB size (or actually to not make such a stupidly small test db in the first place), but as has already been said a much better solution is to use a full size DB with a test server capable of handling it. Anyway, a stored proc that is perhaps handling a significant proportion of a terabyte of data with a shortage of memory is going to be soing a good deal more than 1GB of IO, and there's probably no imaginable way that the same SP handling a similar proportion of 1GB with 0.5GB available is going to be handling anything like the same amount of II, so reducing the store available to SQL Server on the test machine to 0.5GB is not going to give you a clue as to the performance of the production system on the full size DB, so I don't at all like the "correct" answer.