200,000 images in single folder in linux, performance issue or not?

I know an answer was chosen, I want to add a solution on improving the performance, for interest

Querying the directory listing each time will cost the most overhead, if the directory listing returns all results every time.

You can improve performance by storing the listing in an indexed database (say SQLite) and just query the results from there. You can select a subset of records and implement pagination much easier this way, and filter the results too.