I know the evidence is that plenty of people are totally happy with applications running in a browser -- Office Online, Google Sheets, etc. are compelling evidence -- but I strongly prefer dedicated and native applications for something I'll be spending a lot of time using.
I'm not even necessarily blaming this on the performance difference, although that is a pertinent topic, but just the mental structure of something I'm using living in a browser tab rather than actually running on the computer.
Reminds me of reading Stephen King's twin novels Desperation and The Regulators, were the same cast of the same town endured two parallel paranormal storylines. Recommended read to inspire your concept!