Yes I'd do that. My experiences with all the pos coins are that once the number of transaction > 1000, then the wallet can run very slow. I usually transfer the amount to new wallet, and then there will be no problem.

Since many coins are generated by pos blocks, and these are small amount coins each time, you may need to transfer a few times to the new wallet. I think when generating tx out there's a limitation (again in all coins) that max 1024 tx input can be combined into a tx output. So that's why sometimes you see "transaction failed" message. If you see it, just try to transfer a smaller amount.