I'd recommend configuring the full text index for manual population; this will vastly reduce the number of "full-text auto population" messages written to the log.
The Microsoft Docs page shows how to configure a full text index for manual population.
Essentially, you explicitly define the index like so:
CREATE UNIQUE INDEX ui_ukDoc ON Production.Document(...
A trick that sometimes is useful...
MATCH is usually the fastest way to search
MATCH has some drawbacks
LIKE and RLIKE are very slow
When using both MATCH and LIKE, MATCH is done first, thereby providing very few rows to recheck with LIKE:
WHERE MATCH(...) AGAINST(...)
AND ... LIKE '%...%'
(I am not familiar with how NGRAM works, so I can't provide ...