Norris finished where he started in seventh but struggled on the medium Pirellis during his opening stint to lose three places before pitting on lap five of 44 for hard tyres.
The Briton reckoned this part of the race was "terrible" as it left him trapped between defending through the first sector before then being unable to pass later in the lap.
He explained: "It was terrible - it's an honest answer. We were just stuck in a circle of not being able to push enough in the middle sector because of the cars ahead and people [behind] having to lift in Eau Rouge. We were that slow.
"I was getting overtaken before the DRS zone even started. So, we had to try something. We went on to the hards and this was even worse. No one's ever used the hard all weekend.
"We thought it normally kind of suits us, so I think it was the right decision to try. But it was still terrible. I didn't have enough laps to get the tyres in and be able to push.
"I got overtaken on my first lap out of the box."
Norris added that his tyre struggles came independently of the MCL60's downforce levels, saying it is a deeper-routed issue that the team has battled for five years.
Source: Autosport