I noticed sentence "Powered by mempool.space and Coindesk." on your website. Have you checked whether those free API actually let user check thousand address within short time?
All depends on how it is going to be used. If you want to test a bulk of addresses from time to time - then yes, maybe.
If you want to test 1 address every few (mili)seconds, it will be too slow, dedicated (and properly indexed) database will be better.
If OP goes on this route, he could load up the file into an optimized structure in memory (maybe b-tree?) at the start of the day and then just query his own structure every time. This should be quicker than using an actual database.
Actual database also use optimized data structure (such as btree or trie), although it comes down to whether you can utilize it properly or not.