It is a massive difference as JPE1701 said, the press is covering up the massive performance hit in IO operations for Intel. In productivity the losses are up to 30%, but it's up to 50% for minimum framerates (all that matters, really) in games. Titles affected do heavy texture streaming. https://np.reddit.com/r/pcmasterrace/comments/7obokl/performance_impact_of_windows_patch_and_bios/ds88idv/
I really hate to see what will happen once everything is patched. I'm not updating any hardware until 2019 when all Spectre variants are fixed in hardware by Intel & AMD. If I had to buy anything before then, I'd recommend the AMD stuff. Especially the 2400G, love that chip & no Meltdown worries with it.