Slow SDD 250gb internal drive

I own a win 7 pc computer.
Windows 7 Professional 64-bit SP1
Intel Core i7 3770 @ 3.40GHz
32,0GB Dual-Channel DDR3 @ 798MHz
Motherboard Gigabyte Technology Co. Ltd. Z68MA-D2H-B3 (Socket 1155)
4095MB NVIDIA GeForce GTX 1070

with 232GB Western Digital WDC WDS250G1B0A-00H9H0 ATA Device (SATA (SSD))
which its running pretty slow. I ran a CrystalDiskMark 7 test and shows me that it reads and writes around 230mb/s
I have it since a few years now. and I am about to perform new system installation.
Why its going so slow? its at 85% full capacity. thats why? its way too full? Should I back up all the info and do a new format to the drive? will that help to get back to the speed from when I bought it?