However, Fortin said that Windows 7 users could experience freeze-ups while writing small files and see overall performance slow down over time, depending on the quality and age of the SSD they're using. The freezing problem is caused by the "complex arrangement" of memory cells in flash chips, he said, as well as the fact that data must be erased from cells before new data can be written to them. And few SSDs today include RAM caches that can speed up performance, as most hard drives do. As a result, "We see the worst of the SSDs producing very long I/O times as well, as much as one half to one full second to complete individual random write and flush requests," Fortin wrote. "This is abysmal for many workloads and can make the entire system feel choppy, unresponsive and sluggish."

That is despite such as resizing partitions to better fit SSDs and "reducing the frequency of writes and flushes," wrote Fortin.

Even , which was created by Microsoft to take advantage of USB flash drives using solid-state memory to accelerate performance of Windows Vista or 7, will actually slow down when run with most SSDs, wrote Fortin. As a result, Windows 7 will turn off ReadyBoost for SSDs.

Meanwhile, performance degradation over time is caused, again, by the need to erase data before it can be written, and the increasing fragmentation of data on SSDs as they fill up.

Some vendors say they have mitigated the problem on their SSDs, but none claim to have solved it.