Speed up Coding

Hi Everyone,

First time writing VBA code and creating a "Program" as such. So i need some help. I have included my example document below.

Note
*The Modify Vehicle hasnt been coded as yet
*This workbook will be bigger. It will have Vehicle Servicing, Reports on Vehicles, Reports on spending ect.
*The Calendar userform and coding has been downloaded and copied from another website. (This runs quite slow)
*Im wanting to limit my VBA Reference Library as i will be sharing this with friends and i dont know what their computer will have.

Im looking at getting my coding checked to see if there is anything i can do to make it run faster or more efficiently (as the file will get alot bigger)
Im wanting to know as well if there is a better way to reference my Renewal OptionsButtons(Option3M, Option6M, Option12M) and they are also linked to Label(Rego_3M, Rego_6M, Rego_12M) as well as the new expiry date (New_Date label) updates depending on selection

Thank you so much