Of course, it depends on your particular setup and configuration, to determine how much memory you can or want to delegate to the fonts. With the option <#446#>-?<#446#> the default value can be requested, and with <#447#>b<#447#><#448#>bytes<#448#> an arbitrary value can be set at execution.
To find the optimal value for your setup, the logfile is the greatest help in this case too. There after every single entry of a loaded font the percentage of contention of the font memory is displayed.