+1 vote for Verizon message+. The only time it bogs down for me is from poor network coverage. I did use the LG messaging app for a little, but didn't care for the overall appearance. It worked fine though.
I also use textra. I never had freezing with the native app on my ATT V10, but it constantly felt slow. Coming from iPhone it was especially obnoxious. Google Hangouts and Google Messenger also worked well, but Textra was the fastest and most customizable for me.
I have a huge amount of sms. The native app was not behaving well so I switched to Textra. It works great!
Question - and this may help the OP too. Does Textra change the underlying XML data? Can you still switch back and forth between Textra and the native LG sms app?