[turba] Turba hangs w/>500 records, gives "Allowed memory size exhausted" error

[Eric]

Our contacts database has grown to more than 500 records, and now I 
am unable to display the address book.  I can search on certain 
subsets of the address book and display those, but whenever I try to 
display the whole thing (including sorting on columns, which causes a 
redisplay of the whole thing), Turba just hangs and won't continue, 
won't even let me log off (I have to dismiss the web browser and start over).

On another computer with the same OS (Fedora Core 2), rather than 
hanging, I get an HTTP "file not found" error.

It does this whether I have 500+ lines selected to view, or some 
smaller number like 100 (which means the database views in pages).

If I trim back the database to under about 500 records, everything works OK.

In the /var/logs/httpd/error_log file, I am getting entries like:

[client NNN.NNN.NNN.NNN] PHP Fatal error:  Allowed memory size of 
8388608 bytes exhausted (tried to allocate 128 bytes) in 
/var/www/html/horde/turba/lib/Object.php on line 141

I looked at Object.php line 141 and all it says is:

   $this->attributes[$attribute] = $value;

What can I do to increase the "Allowed memory size"?

Eric