Optimising thinking time is underrated. Probably half of the value my company gets from me comes on the last day of a sprint, when there are no stories left and I have a few spare hours to think about areas of improvement instead of rushing to review PRs or finish my own. This is why slack (the concept, not the app/company) is so important.
I have mentioned AQE before in this blog. It is a very important feature: imagine having a table that the statistics metadata said was 100 rows, planned to have a broadcast join but then it actually had 1 billion rows! This is what AQE fixes.
I missed seeing a mention of the tiny ones you can embed in a webpage (like lunrjs, or fusejs, which powers search here), but I found out many tools I may consider using when ElasticSearch/Lucene is overkill.