Cpu Load Problem despite parent/master and no sends routing

Perhaps you should also try bigger buffers ("Block size") for Prefs > Audio > Device. Small buffers need more CPU.

Reaper's 64bit engine is pretty slow on Pentium4 processors! More tracks = more mixing and more CPU load.

Do empty tracks in Folder use up the cpu power ? 

I thought about it.... :-) A track duplicate in a folder in Reaper is in fact something very different to a Logic track duplicated. In Reaper it is still an independent new Audio/Instrument ... whereas in Logic it is more of a lane of the track that only plays its data through the actual Audio/Instrument Track with the FX. Well, I wanted to work on different Tracks ( Guitar1verse1,Gtr1chorus1, Gtr1verse2, Gtr1chorus2, ....and then different Versions of it!!)for structural/workflow reasons (mute, solo buttons...) Free Item Positioning for different multilane Items Versions of a Gtr1Verse1 is a bit messy and tricky in handling when editing/comparing/soloing.... I wish there was a bare Subtrack type/class (without any controls but mute and solo)in Reaper which is just feeding the actual Instrument/Audiotrack FX of the Mixer. Is this the answer to my question? :-) Is this "naked SubTrack Type" not something very very useful ... or is it just something I am looking for? regards