Poor performance on project picker when there are over 3500 projects

Summary

Very poor performance on the project picker dropdown when there are over 3500 projects.

Steps to Reproduce

1. Deploy a new JIRA instance and install Portfolio.
2. Use this script to generate 4000 projects, filling the values at the top prior to running it.

   #!/bin/bash
   PROJECTS=4000
   JIRA_BASE_URL="http://ecrmac-632.local:54593/PS-9149"
   JIRA_USER="admin"
   JIRA_PASSWORD="sphere"
   
   for p in $(seq $PROJECTS); do
       echo -n "Creating project $p of $PROJECTS: "
       PKEY=$(LC_CTYPE=C tr -dc A-Z < /dev/urandom | fold -w ${1:-6} | head -n 1)
       curl -u $JIRA_USER:$JIRA_PASSWORD \
          --header "Content-Type:application/json" \
          -X POST \
          -d "{ \"key\": \"$PKEY\", \"name\": \"$PKEY\", \"projectTypeKey\": \"business\", \"lead\": \"$JIRA_USER\" }" \
          $JIRA_BASE_URL/rest/api/2/project
       echo
   done
   

3. Grab a coffee, this will take a while.
4. Navigate to Portfolio > Create plan.
5. Enter any plan name and hit Next.
6. Switch to Project on the left dropdown then start typing to search for a project.

Expected Results

Project picker dropdown performs fast like the user picker.

Actual Results

All projects are loaded into the dropdown, taking a long time to render and being generally unresponsive.

Notes

• This slowness also happens on JIRA's issue search page, albeit less noticeably, as reported on JRA-63784.

Workaround

None.