I would suggest that you check the condensor (the 'radiator' in front of the radiator) for dirt and 'stuff' and give it a good spray cleaning to be certain that air flow is not blocked. If it's significantly blocked, you might be noticing your temperature gauge showing a bit hotter in normal driving too.

I would also suggest to check that the electric fan(s) work as they should.

Insufficient airflow through the condensor will result in 'not enough cooling' whether from slow driving, where the electric fans cannot keep up with the demand, or airflow blockage.

It is not likely that the insulation on coolant lines is causing you to lose cooling capacity, since the lines have a relatively small surface area. The insulation prevents condensation and water drips in the dashboard and cabin.

You could be low on A/C refrigerant. This can be checked by a technician.

Best regards,

Jim