The Melinda time is a term used to refer a time higher than the current bold time that theoretically could be obtained, but would require extreme luck and/or skill - often both - to obtain. They are almost always caused by the use of random elements.
Skelzie is one special case: its bold route is 454.2, and with Chip's (2U) move to a green button possibly being covered by a blob, 455 may be possible. Whether the pink balls remaining in the telenet that makes up the nine main rooms of the level will delay Chip longer than they do in the 454 route, and whether the Teleport Skip Glitch can even be used effectively with the different ball locations, are unknown because applying and executing the glitch is difficult - and limited to only MS play.
The Melinda time is difficult to calculate because of the large amount of random force floors and the erratic pattern of the toggle walls. When the bold was 476, the time was calculated as 488, but improvements in the non-random area of the level have left this total indefinite.