Earlier it was mentioned that the problem was the seeds or the soil. You responded that it had to be the soil because you were working out of a bulk package of seeds that you've been using (apparently with good results) for the past four years. There are two aspects you can look at with seeds...germination rate and seedling *viability*. Just because the seeds sprout doesn't mean they will grow good. A seed that is getting along in age may germinate just fine...just as it has in the past. But...an older seed's viability to grow into a productive plant may not be good causing it to malinger around, growing slowly, and frustrating the grower.
I recently planted some 4-year-old Big Beef and Cupid cherry seeds that germinated in five days...the Big Beefs had a 75% germination rate and the Cupids an 83% rate. So far they're looking healthy, but time will tell me if the plants will be viable. The peppers (unsurprisingly) did not have as good of a germination rate. I've got them sitting beneath a bank of LED shop lights. I missed a day checking and they got a little leggy before moving close to the lights. If they don't show good growth in a week or so I'll be ordering some fresh seeds.
Here they are eight days after sowing: