.mts format issue in premiere pro cc

Hi

I've always experienced problems in editing with .mts video files (recorded with a panasonic camera) and most of the time, I'd rather convert them to other formats (like mxf or h264). mts files slow down the whole program, you can't play nor edit them correctly... and especially when making a multi-camera sequence, it get worst. Does anyone have an idea on this? Should I install a codec or....? I've had this issue in every edition of PP (including 2014, 2017, 2018)

I work on a PC

Thanks