I have 240GB Lexar NQ100 SSD in my old laptop (max read/write speed 500MB/s), split in two 100GB partitions, first partition is OS Windows 7 other empty so far.
I have copied 40GB of files one big 25gb other small from one partition to another and my copy speed started first at 300 MB/s then 100 MB/s an then ended at regular 30 MB/s and my whole system lag i could not open Firefox took ages to load and my DPC latency had some red spikes (DPC Latency Checker).
As soon as copy finished system worked good once again, it even felt like programs that are already loaded were not working properly like Firefox could not connect to internet and overall system lagged even though CPU use was low and plenty of RAM.
Here's another latency checker tool.
My SSD is aligned using AOMEI Parition Assistant
So my question is why i get such a degraded performance out of my SSD, even worse than regular HDD would give me while copy speeds are very low as well.
Was it SSD issue or storage controller issue or driver issue, what test procedure i can preform to find out what exactly is causing this lag?
Edit: Benchmark.