Field in Customer Portal loaded slow when it contains a lot of values

Issue Summary

Currently, when a request form has a field with custom field type "Select List (single choice)" and the value contains 3.5K value, the field will be loaded slow.

Steps to Reproduce

1. Create a "Select List (single choice)" custom field.
2. Add around 3.5K value
3. Then, add the field to request type form.
4. Go to Customer Portal and load the field.
5. Try to key in any value to search it

Expected Results

The field will loaded fine and when key in the wording will be smooth.

Actual Results

The field loaded slightly slow and when key in the wording it has a sticky effect. The word display a bit slow.

Workaround

Reduce the number of field values.