Memory Allocation Errors throughout Control Panel after using Member Import Utility

• EE Version: 3.5.3
• PHP Version: 5.5.9
• Server Type: Linux

After importing the approximately 3227 Guest accounts on our system (Which does so successfully.), the control panel starts having issues with opening Entries, and gives Memory Allocation Errors.

If I manually remove all Guest accounts (using phpMyAdmin), the control panel starts to work again.

Member Fields:

• All default For Member Group
• Address
• City
• State
• Zipcode
• Monthly Newsletter Opt
• Weekly Newsletter Opt
• Volunteering Opt
• Promotional Booth Opt
• Certified Test Results