The bottleneck of script components is the data piping (What goes in, what comes out). Its is more complicated and slower, but it makes scripting easier for casual users. You can bypass this like shown in the link below. Furthermore, parallel programming is not always faster. Especially if you don’t correctly identify the bottleneck.
Writing a custom component will always be faster without any hacks. But as I said, you can improve scripts by improving data input and output by doing the following:
See this: Evaluate vs smaller than vs C# component speed difference - #3 by TomTom