General

Ivory's feature implementation was designed to work on a wide range of computer speeds. Each feature has an On/Off button in order free up resources on older computers, or those with significant bottlenecks, or otherwise during a resource-intensive session. Every system, no matter how meticulously optimized, will be limited by one of these three things:

• CPU/bus speed
  
• Hard drive speed
  
• RAM
  

Ivory will bump up against one of these more noticeably on slower computers, but you'll hit one of these when pushing Ivory on any computer.

CPU/Bus Speed

The best way to determine if CPU/Bus speed is too slow is to call up and watch the host's CPU usage meter. If the meter maxes out, then you will need to reduce CPU load. Turn off any unnecessary features:

• Sustain Resonance
  
• Ambience
  
• Chorus, etc.
  
• Set Key Noise to zero (12 o'clock)
  
• Reduce the number of maximum voices

Disk Performance

Since Ivory uses more sample data than will fit into RAM, it uses a technique called "streaming" to read sample data directly from a hard drive. The drive that Ivory uses is the one that contains the Ivory Items folder. Ivory can only play back as many voices as your current setup will allow. To keep Ivory performing its best, it is important to know how to best set up your Ivory installation and keep your disk running efficiently.

For starters, install the Ivory Items folder on its own dedicated hard drive, at least 7200 RPM. Note that internal laptop drives are slower than this. Also take into account the hard drive interface. SATA is perhaps the best choice these days, but if this isn't convenient, choose Firewire 800 if you can.

Although Ivory will work on a USB drive, this should be your last option if no other is available. Choose Firewire 400 over USB 2.0.

Consider creating a two-disk striped RAID with a fast interface like SATA or Firewire 800. RAID arrays can easily be made on OS X using Apple's Disk Utility program.

Avoid installing Ivory onto a disk that is already close to being full. The sample data will become fragmented, and will reside on a slower portion of the disk, both decreasing Ivory's performance.

Partitioning a disk drive into multiple partitions (volumes) is generally a bad idea. Separate volumes on the same drive does not count as two separate disks. It also may force Ivory's sample data to reside on a slower part of the disk.

Slow disk performance is indicated by the appearance of the words 'Slow Disk' appearing just to the left of the MIDI light on Ivory's main page. This is often accompanied by a 'click' as a voice abruptly stops playing. Although you should consider the recommendations in the preceding paragraphs first, changing Ivory's Buffer Size may help. For newer computers, setting this to Small my yield better results. Ultimately, you may may need to reduce Ivory's voice count if your current system simply can't keep up.

RAM usage

Unlike OS 9, OS X uses a virtual memory system that cannot be turned off. So what may seem like a performance problem in OS X may in fact be related to RAM. If you are experiencing dropouts without the Slow Disk message appearing to the left of the MIDI lights on Ivory's main page, then it's probably a RAM issue. RAM issues can also become apparent when other sample-based plug-ins (eg samplers or sampling reverbs) are used alongside Ivory.

The following methods will reduce Ivory's RAM usage:

• Turn off Release samples
  
• Turn off Soft samples
  
• Decrease Ivory's Buffer Size
  
• Choose a keyset with fewer dynamic levels

Latency

Latency is one of the most misunderstood topics in the industry. Ivory itself has very little if nothing to do with latency. The speed of your computer will have a significant impact, but it is mostly introduced by the audio hardware in your system and can be controlled with the hardware buffer size setting in your host software.

In Digital Performer, the setting is called "Buffer Size":

Setup > Configure Audio S System > Configure Hardware Driver

In Pro Tools, the setting is called "H/W Buffer Size":
Setups > Playback Engine

In Logic, the setting is called "I/O Buffer Size":
Preferences > Audio > Drivers > Core Audio

Default values are usually set to 256 or 512. Selecting a lower value will improve latency. The trade-off is CPU load, so setting too low may cause other performance problems.

In addition to hardware buffer size, increasing your hardware sample rate will also improve latency.

And finally, some effects plug-ins impose a delay due to the nature of how they process audio. The host may compensate for this during normal session playback, but will be exposed while playing Ivory in real time.