Loading Issues for Asia users

Users of my app are mostly from South East Asia. It’s a timekeeping app where they need to clock in to start their work shift. The problem is that sometimes, the app takes too long or even fails to load resulting to some users clocking in late, therefore affecting their pay.

While troubleshooting, we tried different browsers, incognito, cleared cache, restarted PCs, to no avail. We were still stuck with just a blank browser page and spinning circles. What worked was a VPN to a US server. The app loaded instantly.

I am now assuming that the loading issue is due to the app being hosted in a US server. I understand that the enterprise plan provides an option to choose a hosting location but it is too costly and premature at this point. I only have around 300 users using 300k WU per month on average and currently in the Starter Plan.

Do you have any recommendations to optimize this without subscribing to the enterprise plan?