Engine idle in and out of clutch

Whilst stopped at a light (engine all warmed up) if I have the clutch peddle down my idle is approx 900, but if I have the car in in neutral and the clutch out, the engine drops to 600 - 700.

I presume this is relatively normal but wouldn't think there would be a huge difference. I know the engine is turning the shaft in the gearbox, but should it be that noticeable ?

Any ideas ?

Thanks

Usually it is the opposite - when you step on the clutch (in neutral) the drag from the throwout bearing drops the idle slightly (maybe 50 RPM). The only time I've seen it drop on taking your foot off the clutch pedal is during the winter (well below freezing) with thick, 20w-50 oil in the transmission. In that case the oil is so stiff there is drag on the input shaft - even in neutral.

But if you are dropping 300 RPM upon taking your foot off the clutch then something is dragging - maybe a bearing. Or maybe you have really thick oil in the transmission?

Took it out for another run & yes, embarrassed to say, I had it the wrong way round.

Have an oil leak - rear seal & waiting for the speedi seal, so will check out the barings.

Thanks

Then it is either friction from the throwout bearing ( more than usual) or the thrust washers are shot (that is more serious).