Quicktime Pro Player lags on Windows 7

I have QuickTime Player Pro 7.7.2 installed on a Win7 (64bit) SP1, running on a Core i7 system.

Although 1080p playback is smooth, QT Player lags when I pause and jump to a position, or use arrow keys to move frame-by-frame.

It waits up to 3-8 secs before responding.

For instance; If I hit space, it starts immediately but if I pause playback, tap right arrow to go 1 frame forward, it takes about 7 secs to display the next frame.

That is weird.

Anyone experiencing this?