I am curious, generally speaking, has anyone seen performance issues using Custom Transactions? We create around 5000 per day. We are looking to enable the feature. I have not seen performance issues with these in the past, but wanted to poll the crowd for confirmation. Anyone using these with high volume?

I haven't seen performance issues in past instances where I've used them at between 5k and 10k per day

No performance issues here either with custom transaction records. However, working with one of our clients, we did uncover a bug that was introduced in 2021.1 that prevents users from being able to inline edit multiple custom transaction records. NS support acknowledged it as a defect (#628878) which should be resolved in the next release.