To ensure that your Tag Manager installation performs at its best, keep the number of tag configurations in each container at a reasonable size. For containers that have large numbers of tags, triggers, and/or variables defined, or have large custom HTML tags, a Size indicator may appear in Tag Manager on the Versions pages. If the Size indicator value is above 70%, you should take steps to optimize your container configuration.
Clean up your container
Combine multiple similar tags with slightly different configurations into a single tag that uses variables to dynamically set the values of certain fields. Example: Ten similar tags, each configured with a trigger that tells each tag to fire on ten separate pages, can be combined into one single tag/trigger combination that uses a Lookup Table variable to set the values of the relevant fields.
Remove any unnecessary tags and variables that are no longer needed. If a tag, trigger, or variable is never used, then it is taking up space in your container unnecessarily.
While it is good to consolidate tags with Lookup Table variables, an excessively long lookup table can also reduce performance. In most cases, you can reduce the size of long Lookup Table variables with a RegEx Table variable.Split large containers that span multiple sites (or sections of very large sites) into smaller containers. 360 customers can use zones to load multiple containers conditionally.
Be smart about custom code