Small holes in pepper leaves could be caused by flea beetles, but these won't stop your plants from growing. What's causing the plants to grow slowly is the weather. Peppers need hot, sunny conditions and across most of the country, the weather has been so cold and wet that plants like peppers are stalled. Once the weather warms up, your plants should take off. As far as the potential flea beetles are concerned, you can spray your plants with an insecticidal soap. You can buy this at most garden centers or home stores. Follow label directions.