Immediate help needed (text problems)!

Every time I add any text to my video it becomes slow and choppy. How do I fix this? Also here is my specs:

OS- Windows 10 (64 bit)

CPU- Intel® Core™ i5-8400 CPU @ 2.80GHz

GPU- Radeon™ RX 580

RAM- 16 GB

Hard Drive- 500GB SSD