Here is what I think could help.

Having all your audio files on a seperate SSD drives internally or on ESATA
Shutdown anything that can use CPU or drives (like antivirus or other health softwares)
In Samplitude, go into the settings and ajust how many CPU are used for a higher number, most I7 go up to 8. (I'd put 6 so other process can have some ressources)
Also, I suggest you use busses for all effect that can be applied to more than one track.. exemple, send all your flutes to the same EQ..
Do mixing and mastering processing in seperate projects (mix first and export) start a new project and then master...

I suggest you look at your resource monitor to see if there is a resource (CPU, memory, disk etc) that is the bottleneck.

Before you start a complex mix, go Ctrl-Alt-Del and select "Start Task Manager". In Task Manger, click the Performance tab, then select Resource Monitor at the bottom of the window. In the Overview tab, you have four graphs on the right, and from those you should be able to tell which is struggling. Beware that the graphs are auto-scaling, so you can get a graph that peaks to the top of its window, but its scale on the right may be 0 to something low. Start the mix and keep and eye on the resource usage.

Other tabs in the Resource Monitor allow you to examine the individual resources in more detail. You can swap around what you look at while the mix is in progress.

PC made the very good point that it's important to have the audio files on drives (preferably two, one for read and one for write) that do not have any operating system software on them. Use of third-party effect plug-ins can also have an impact on resource usage, particularly if they reduce their imprint by heavy use of virtual memory.

I will add to the others great advice, that on a standard HDD 64 tracks will bog it down. When you move into SSD drives they handle hundreds of tracks with ease.

Boswell, post: 460745, member: 29034 wrote: PC made the very good point that it's important to have the audio files on drives (preferably two, one for read and one for write) that do not have any operating system software on them.

Does this mean you have to copy/paste each take into your audio read drive? Im not following exactly what your describing.

kmetal, post: 460752, member: 37533 wrote: Does this mean you have to copy/paste each take into your audio read drive? Im not following exactly what your describing.

Sorry, yes, I was trying to be concise in covering a range of possibilities, and it didn't really work.

What I've found when using a dedicated audio hard drive for mixing high track-count songs is that there can be a lot of head-movement time spent shuttling backwards and forwards for reads and writes from/to different areas of the disk. I experimented by getting a second audio drive and using that for the scratch area and for writing the 2-track mix. I was surprised by how much time I gained.

These days, I find that my recordings are usually 16 tracks or fewer, so I rarely do high track-count mixes. The high count mixes I do are often mix-only jobs from other recordists, and I can flinch when I see the track usage (14 microphones on a drum kit - come on!).

As K mentioned, this separation of audio read and write is probably rendered obsolete by solid-state drives (SSDs), which have effectively zero latency compared to a rotating drive. I may be being a bit conservative, but I have my Windows OS on an SSD and still rely on HDDs for audio.

I'm not sure if any DAW actually suport a drive to read and a drive to write seperately.. But in fact they would need to be synchronised cause when you stop a recording and start the playback the files you need to be moved over.. Teddious actions.. !! We may create a new Raid format for this !! ;)

So you guessed it, that wasn't what I ment.. What I was saying is having a drive for the OS, a drive for the audio files and even a 3rd drive for vsti samples..