I am not aware of any traffic issues north of I-26 because I do not travel that way, but from what my father has mentioned to me in his travels from Lakeland, FL to Fuquay-Varina, NC to visit my brother is that the issues he would encounter would start north of I-20 and be intermittent between there and I-40.
This is basically my NC-FL leg of the trip. Leaving Davenport, FL at 5am, I can generally make it to the Triangle by 2-3pm depending on how many times I stopped. I've only done the trip north on a weekday, even then its a mess in southern SC. Weekends, if you leave early, you can avoid most of the SC traffic.
It is good to see North Carolina begin to widen I-95. I imagine is must be stressful to regularly travel I-95 anywhere along the East Coast based on what I have read. The last time I was on I-95 for a good stretch was in 2005 taking a delivery from Alexandria, VA to Miami Beach. It did not seem very stressful then, but that was 17 years ago.
Once you get north of the Capital Beltway, it generally isn't too bad mid-day and decent alternatives open up (US-50/301, MD-3/I-97). Midday is generally not a problem traveling through NJ now that the NJ Turnpike is widened.