Fetching Customer Request Type Field for lots of issues is slow

Issue Summary

When fetching the Customer Request Type or Request Type field for a large number of fields using the rest/api/3/expression/eval endpoint, the response is very slow.

Steps to Reproduce

1. Send a request to the above endpoint with a payload similar to the following (in order to get the request type field value for multiple issues - up to 1000) 

   {
     "expression": "issues.map(i=>[i.id,i.updated,i.customfield_10010&&(i.customfield_10010.requestType&&i.customfield_10010.requestType.serviceDeskId+\":\"+i.customfield_10010.requestType.id+\":\"+i.customfield_10010.requestType.name||false)])",
     "context": {
       "issues": {
         "jql": {
           "query": "project = \"My Service Desk\" order by updated asc",
           "startAt": 0,
           "maxResults": 1000,
           "validation": "none"
         }
       }
     }
   } 

Expected Results

Should return a response within 1-2s

Actual Results

The response returns after 5-9s

Workaround

Currently there is no known workaround for this behaviour. A workaround will be added here when available.

However, the cause has been determined we have a proposed solution to fix this issue