Ok, you seem to have been brainwashed by the review sites into thinking that SATA3 is junk and that you must have a PCIe SSD.
How fast a drive feels depends on how long you have to wait (seconds) for it to complete an operation. MB/s is the
inverse of wait time, and so the benefit of faster drives is horribly exaggerated if you compare MB/s. Look what happens if you compare how long you have to wait for the following drives to load a 1 GB level file in a game:
8 sec = 125 MB/s HDD
4 sec = 250 MB/s SATA2 SSD
2 sec = 500 MB/s SATA3 SSD
1 sec = 1000 MB/s PCIe SSD
See how every time you double MB/s, the reduction in wait time is halved? That's why those really big MB/s numbers don't really matter - the bigger the MB/s, the smaller improvement it represents in terms of wait time. They exaggerate the actual benefit you'll see when you're sitting in front of the computer. The reason the industry and review sites measure speeds in MB/s instead of sec/MB is because it
exaggerates the benefit of tiny increases in performance, thus making you want to go out there and spend lots more money on new technology which gives only a tiny improvement in performance. It's just marketing.
On top of that, a game level isn't going to be a 1 GB sequential read. More than likely it's a bit of sequential reads + a bunch of random small file reads. And all these drives are the same speed at reading random small files - about 25-35 MB/s and 70k-100k IOPS. So the speed difference between these drives is going to be even smaller, or even nonexistent.
In real-life tasks, the only people who'll really benefit from the PCIe SSDs are people who regularly work with large sequential files. e.g. Real-time video editing. Even SATA 3 is overkill. When you compare SSDs on SATA 2 vs SATA 3, SATA 3 performs substantially faster in benchmarks. But in real-life tasks, their speed is nearly indistinguishable.
http/www.tomshardware.com/reviews/sata-6gbps-performance-sata-3gbps,3110.html
And the difference between SATA 3 and PCIe in real-life tasks is even smaller. Compared to a HDD, the SATA 3 SSD reduces your wait time in the best case (sequential reads) by 8 seconds, the PCIe SSD reduces your wait time by 9 seconds. That's the real-world difference you're going to see - almost negligible. In the most extreme case, compared to a HDD the SATA 3 SSD gives you 89% the wait time reduction of a PCIe SSD. In most real-life cases, the difference is even smaller. So don't fret over your laptop not supporting PCIe SSDs.