One can never have enough single-threaded performance, even when dealing with mere web browsing. Fractions of a second add up to seconds, and seconds to minutes. However, there does come a point where dealing with the bottleneck of disk read/writes should be addressed first over CPU speed if you want to make the "ultimate browsing rig".
True. I just did a test, between my:
1) i3-6100 (stock, 3.7Ghz), 2x4GB DDR4-2800 @ 2133, Silicon Power 240GB MLC SATA6G SSD, Win7 64-bit, crunching NumberFields@Home on 3 out of 4 virtual cores
2) G1820 (stock, 2.7Ghz), 2x8GB DDR4-1600 @ 1333, VisionTek GoDrive 120GB MLC SATA6G SSD, Win7 64-bit, crunching NumberFields@Home on 1 out of 2 cores.
3) G4400 (OCed, 4.455Ghz), 2x4GB DDR4-2400 @ 2520, Samsung SM951 PCI-E 3.0 x4 AHCI M.2 SSD, Win7 64-bit, crunching NumberFields@Home on 2 out of 2 cores.
I was using the same model mouse (an EVGA laser gaming mouse), and was at the AT forums index. I clicked on CPUs and Overclocking, and then used the back and forward buttons to flip back and forth.
All three rigs had roughly the same subjective timing. Although, I was crunching on both cores on the G4400, and only one core on the G1820.
If I shut down the crunching on the G4400, it seems ever imperceptibly faster.
Edit: Peacekeeper results, Firefox 44.0 x64:
1) 6810
2) 4746
3) 7846