Windows 8's user share growth slowed significantly in July, hinting at further trouble for the struggling operating system, new statistics from an analytics company show.

The operating system's user share grew by the smallest month-over-month amount since its launch in October 2012, said Web measurement vendor Net Applications. At the end of July, Windows 8 accounted for 5.9 percent of all systems running Windows, an increase of three-tenths of a percentage point compared to June.

From November 2012 through July 2013, Windows 8's user share grew by an average of six-tenths of a point each month, with lows in February and April of five-tenths and a high in June of nine-tenths of a percentage point.

July's increase was about a third of June's.

The slowdown is most likely tied to the continuing problems of the personal computer industry, which has seen five consecutive quarters of contracting shipments. The consumer side of PC sales has been especially hard hit, as customers opt instead for tablets in lieu of new PCs, either letting their current machines age even more or forgoing purchases entirely.

By IDC's estimates, PC shipments fell 11 percent in the second quarter compared to the same period the year before. Consumer sales have tanked even more, as businesses accounted for the majority of purchases.

Windows 8 has been hit particularly hard by the downturn in consumer computer sales, since enterprises have been hesitant to migrate, leaving only individuals and very small businesses willing to take the plunge and run the radically-changed OS.