This issue has been fixed in WPLMS 2.8 update

The recent WordPress update is causing some issues with the third party plugin “Envato Market”. This results in very slow loading of the WordPress Admin – Updates page.

Since the Envato market plugin is “optional” for updates as WPLMS itself has update code, you can deactivate this plugin.

To deactivate this plugin simply go to WP Admin – Plugins area and deactivate the Envato market plugin.

In case you’re not able to open WP Admin – Plugins area, please try following steps :
1. please login to your Ftp or cpanel-> file manager .
2. Then goto wp-content/plugins folder find folder named “envato-market”
3. rename it to “envato-market_disabled”   .

Optionally , also follow this guide : https://www.ostraining.com/blog/wordpress/disable-a-wordpress-plugin/