I know nothing about batching (I am not even sure what that means)...
I have a script where I measure, how long it would take for one writeBlocking to write a bunch of tags...
In v8.1.28 it takes 30-50ms to write. On 8.1.34 was 1000-1500ms.
That's all saw.
I remember that I tried 8.1.34 to try this 'new' feature about Tag reference...
And I think that when I enabled Tag Reference Tracker Store all of that 'slow writes' started.
But when I disabled the Tag Reference Tracker Store again, it was no better, so I downgraded back to 8.1.28...