IMKClient Stall detected

I was trying to test the application on Mac. The approach of using microphone input is working fine, but there is problem with the approach which is using File input. I'm getting error message like this:

`java[72481:674880] IMKClient Stall detected, *please Report* your user scenario attaching a spindump (or sysdiagnose) that captures the problem - (imkxpc_attributesForCharacterIndex:reply:) block performed very slowly (1.15 secs).`

It's being shown as soon as popup window for choosing file is being opened.

Start by reproducing the issue on Mac with the file-input approach and compare it with the working microphone-input path. Focus on the file-selection popup, where the IMKClient Stall message appears. Done means the file chooser opens without the stall and file-based transcription proceeds normally.

索引モデルが issue の本文から書いたものです。