If you can not anticipate when you will need to trigger a sound, you should organize your Cues into smaller CueSheets. These CueSheets can then be loaded quickly when the player reaches an area close to where the Cues may need to be triggered.

Note on streaming

In the cases where streaming playback is acceptable (i.e. when the playback delay is not severe and a sufficient number of streams can be played), it is also possible to avoid having many small CueSheets.
However, it is necessary to make sure that streaming playback will not affect loading times too much (both for audio and other data).