An application's overall font performance could decrease if a large font cache forced the paging of more segments to the disk. With previous font technologies, this could occur even in situations that were not “low memory.” Because fonts are cached glyph by glyph as they are used, however, less memory is used for the cache than would be required to keep the corresponding raster fonts in memory; this leads to a net performance gain. The only time the font cache uses more memory than fonts required in earlier versions of Windows is when multiple logical fonts would have been mapped to the same raster font. Typically, however, any additional swapping to disk caused by these larger caches is still faster overall than discarding and subsequently re-rendering bitmaps.
Hard-disk space is not a large problem for TrueType fonts, although more disk space is required for fonts with the introduction of TrueType. The two reasons for this increased space requirement are that raster fonts are shipped with TrueType fonts, for backward-compatibility reasons, and that users may have preexisting soft fonts on their hard disks.
Hard-disk space is not the only limitation imposed on TrueType fonts. GDI imposes an internal limit to the number of TrueType fonts that can exist simultaneously on a system. The maximum number of physical fonts is 1170. (The maximum number of logical fonts that can exist simultaneously on a system is 253.)