I am using a P4 Core 2 CPU with ASIO driver for the soundcard (Audiophile 192)
I used to get a performance index of 19-20.
Lately the performance index is hovering around 16.
I have not change any hardware. I also do not experience any change in the
performance while playing
What can be the cause of the drop in the performance index
Three possibilities I have seen. One is to make sure the power settings in Windows (assuming you are using a PC not a MAC) are set to maximum performance (not balanced or some variant for saving batteries in laptops). Windows VISTA defaults to "balanced" mode which is not the highest performance level of a machine. Other versions of Windows may do something similar. This causes a peculiar variation in the message which goes away if you force the computer to its full performance mode. A second possibility is if you changed the sampling rate from a lower to higher setting, this seems to affect the rating. The last possibility is I have noticed a difference in the performance level depending on what I am playing. Playing lots of notes and holding the sustain pedal tends to result in a decrease in performance level. I am using an AMD Turion 64 dual core (1.8 gigahertz) and I have noticed performance levels between 13 and 16 depending on what I am doing. Experimenting, I can always get polyphony at least to 150 or higher, which seems to be sufficient for everything I do. In fact, I have to work hard to push polyphony that high (not playing naturally) to eventually get an overload message. Hence, I don't pay much attention now to the performance rating.
I just found a fourth reason that might slow Pianoteq down (long time since my last post about this). In Windows VISTA (may be true for Windows XP, also), there is an ability to change the priority of a process in Task Manager (which you get to by hitting CTRL-ALT-DEL, simultaneously). Under processes, you can right click on any process and use the "Set Priority" option to change the priority. I often change the priority to "high" now, since it seems to prevent other programs (running at "normal" priority) from getting as much CPU time and I stop getting occasional drop outs in the sound, while playing. This is particularly an issue when running Cantabile (at least for me), with the Garritan reverb I've been using. I have not noticed drop outs when running Pianoteq stand alone. I also suspect setting a higher priority would tend to make Pianoteq report a higher performance index, though I have not tested this.
I wanted to find a way not to have to manually set the priority to "high" each time I play the piano. So, I searched on the Internet and discovered you can make a batch file to run a program and set the priority, automatically. I used Notepad to create a text file called "Cantabile.bat" which is on my desktop. The file has the following typed command line:
start /high C:\Progra~1\Topten~1\Cantab~1.2\Cantab~1.exe
The "start" command tells Windows to run a program. The "/high" sets the priority the program will run at. The rest of the line is the path to the program I want to run. Obviously, this could be done for the stand alone version of Pianoteq, too. Notice, the batch command follows the old MSDOS path shortened names convention.
Apparently, running batch files requires using old 8 character or less names of MSDOS for directory names and file names. Often, this means cutting off the full name of a directory or file at the 6th character of a name and then adding ~1 for the last 2 characters. This is not always true and I had to use the "Command Prompt" with the "dir /x" command to figure out the entire path. This means using "dir /x" and using "cd" to change directories to each subdirectory level below it, which allows you to figure out the entire path and name of the file you want to run, in the 8 character convention.
There are 6 priority levels in Windows VISTA: Low, Below Normal, Normal, Above Normal, High, and Realtime. Reading on the Internet, other people recommend not using the "Realtime" priority, since if a program crashes (something I have never seen Pianoteq do in the last year of much use - kudos to the Pianoteq programmers), it is very difficult/impossible to shut down a program without turning the computer off.
This is a long post, but I thought some people would be interested.