System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 451.67

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-08-05 22:29, hash: rB675700d94892
Worked: (newest version of Blender that worked as expected)

Short description of error
Highlights in the viewport render image/animation seem to be clamped/clipped. The viewport render image/animation is in a lot of cases a lot faster than the normal rendering with either F12 or ctrl+F12.
I`ve read that the clamping has a reason/intention behind it, though i`d love to know wether you can switch it off or if that`s ever going to be a feature since it would make eevee so much faster than it currently is without having to compromise
samplecount or other details. (Up to 4x times faster)

Exact steps for others to reproduce the error
Add a plane on a fresh project and get an angle where you can see the highlights of the sun or point light. Slightly increase the lights brightness and compare the viewport to the rendered viewport image.