Alignment slows down significantly during textgrid export

[Barham-K]

Debugging checklist

[ ] Have you read the troubleshooting page (https://montreal-forced-aligner.readthedocs.io/en/latest/user_guide/troubleshooting.html) and searched the documentation to ensure that your issue is not addressed there? yes
[ ] Have you updated to latest MFA version (check https://montreal-forced-aligner.readthedocs.io/en/latest/changelog/changelog_3.0.html)? What is the output of mfa version? 3.0.3
[ ] Have you tried rerunning the command with the --clean flag? yes

Describe the issue
When running mfa train on a corpus, the process slows down to a halt in the "Exporting alignment TextGrid to <output_path> phase"

For Reproducing your issue
Please fill out the following:

1. Corpus structure
   • What language is the corpus in? English
   • How many files/speakers? 104,000 files, 1000 speakers
   • Are you using lab files or TextGrid files for input? lab files
2. Dictionary
   • Are you using a dictionary from MFA? If so, which one? no
   • If it's a custom dictionary, what is the phoneset? IPA
3. Acoustic model
   • If you're using an acoustic model, is it one download through MFA? If so, which one? no
   • If it's a model you've trained, what data was it trained on? Librispeach English 360, LjSpeech, and others

Log file
Please attach the log file for the run that encountered an error (by default these will be stored in ~/Documents/MFA).

Desktop (please complete the following information):

• OS: Windows
• Version:11
• Any other details about the setup (Cloud, Docker, etc)

Additional context
Add any other context about the problem here.