I just checked my with my host on this, and I’m having similar issues with the X loading screen not going to the editor. this was their response when I asked my host to up mt PHP limit:
JC,
Your server is actually running PHP 5.6 with a memory limit of
128MB by default. Their concern of 40MB limit should not be an issue for
you.
This could be caused by PHP memory limit exhaustion. Please keep in mind that even if your server has already being set at 128MB, Wordpress on the other hand will ONLY attempt to increase memory allocated to PHP up to 40MB (code is at the beginning of /wp-includes/default-constants.php) for single site and 64MB for multisite, so the setting in wp-config.php should reflect something higher than 40MB or 64MB depending on your setup. You must explicitly define the 128MB memory in your wp-config.phpm so that WordPress will expand the use of the PHP memory.