I made a file of 9s and it took about a second. I made a video: https://moderncsv.com/videos-temp/load-image9.mp4

You have to change the setting in the Settings file (Edit Settings command) under the "User Value" column. Changing it under the "Default Value" column is a common mistake that's really my fault, so I intend to rectify it soon.

If it still doesn't perform like that for you, let me know.