By unstable, do You mean that the website is slower than expected?
If this is the case, kindly understand that WordPress slowness can be caused by poorly optimized or heavy WordPress themes, plugins, etc.
Please try a few basic troubleshooting steps:
- Flushing any caching plugins you might be running, as well as browser caches.
- Deactivating ALL plugins temporarily to see if this resolves the problem (plugin functions can interfere). If this works, re-activate them individually (one-by-one) to find the problematic plugin(s).
- If that does not resolve the issue, try switching to the unedited default Twenty Fifteen Theme for a moment using the WP dashboard to rule out any theme-specific issue (theme functions can interfere like plugins).
- If that does not resolve the issue, try resetting the plugins folder via FTP or file manager application from your cPanel. Sometimes, an apparently inactive plugin can still cause problems
If any other issues occur, feel free to submit a support ticket from Members Area -> Help Desk section.