If you don't need DLRS, that's a different story. But if you're getting timeout issues, you might consider whether you need your rollups to run in realtime or whether you can switch to scheduled rollups that won't run synchronously with your import/update. See here.

If the NPSP customizable rollups are doing what you need, that's great! Use those for all the donation stuff. But NPSP rollups only apply to donations (opportunities) and GAUs. DLRS is for everything else. 

Salesforce standard rollup summary fields, however, haven't gotten any updates in forever. Anything your org was doing with DLRS before probably still can't be done standard.