More than 42% of PC users neglect to defragment their computers, according to Vizu. Nearly 16% of those who answered the poll said they had no idea what disk defragmentation is, while more than 26% said they never defrag their machines. The remaining respondents said they frequently defrag their systems using either a built-in manual defragmenter (44.9%) or a standalone utility that automates the defrag process (13.1%).