Fulltext search is slow in Workbook 2021 due to missing index on VAULTTEXT.TEXTNAME. OR condition in fulltext search query in Workbook 2021 release is causing slowness, as it is not using index. Workbook 2019 query does not have OR condition in it and fulltext search was faster in 2019 release.

A fix made for 'Request to search by file name in attachments' (NBK-31396) in the Workbook 2021 release caused this new issue.

Jira Defect NBK-34108 entered for it with the description given below.
NBK-34108: Fulltext search is slow due to missing index on VAULTTEXT.TEXTNAME

It is now fixed in the upcoming Workbook 2023 release. It is also back ported to Workbook 2022 HF1, 2021 SP1 HF4 and 2021 HF3 releases.