in, , \wp-content\plugins\nextgen-gallery\nggfunctions.php
after (line 129), 'fx:"'.$ngg_options['slideFx'] . '",' .
Add 'speed: 1000,' .
Here it generates loop plugin parameters.
Update: for NextGen v2
- . , , . jquery.cycle.all.min.js . jquery.cycle.all.js . , speed:1e3 .
. jquery.cycle.all.min.js . -, , .
, .