The general experience is that without an appropriate account management scheme, a steady stream of stake txs inevitably translates into an ever-increasing demand on the CPU as the client thrashes through the accumulated stake txs, calculating each one's contribution to the overall stake weight.

(Forensic archaeology informs me that subscribers to the original Slimcoin thread had worked this out for themselves but the lesson had gotten somewhat lost in the mists of time.)

The Sprouts codebase is very close to Slimcoin's and several Sprouts users were reporting client issues with excessive CPU usage and the Windows client crashing at frequent intervals, identical to those experienced by some Slimcoin client operators.

The exchange reported that the Sprouts wallet crashed every few minutes, a severity apparently not experienced by any other operator of the Sprouts client. Whilst it is possible the exchange were experiencing some totally unrelated problem that was uniquely specific to their set-up, one would expect them to be motivated to solve their specific issue rather than bail out by de-listing the coin. But, as the man said: “It’s 2017 and nothing makes sense any more”.

IMO it's a reasonable conjecture that exchanges which configure their Sprouts or Slimcoin client to earn mint-by-proof-of-stake rewards on client deposits are likely to experience this problem to a significant degree unless the stake calculation CPU demand is adequately supported with additional compute resources.

(That's my understanding at least. Happy to be corrected)

Cheers

Graham