Steps to reproduce:
1. Create a new User Group:

• Name = Test
• Add template permission to "Templates/Applications" to "Read-write"

2. Create a new User:

• Name = Test
• Password = zabbixzabbix
• Groups = Test (the newly created user group)
• Permissions->Role = Admin role

3. Log in as the new Test user
4. Open Data collection -> Templates

Result:
Very slow loading: ~40 seconds

Expected:
Performance is fine on 6.4 Affects latest 6.4 too