https://www.universityofcalifornia.edu/infocenter/ug-outcomes lets you check frosh and transfer graduation rates at UCs (which, along with CSUs, target having about a third of graduates originating at community colleges).
It looks like at UC overall, transfers’ 2-year graduation rates are lower than frosh 4-year graduation rates, but transfers’ 3- and 4-year graduation rates are higher than frosh 5- and 6-year graduation rates. This suggests that transfers are more likely to finish, but more likely take an extra quarter or semester beyond the nominal time (average time to degree for 2010 entrants to UC overall was 4.18 years for frosh, 2.38 years for transfers). The need for extra quarters or semesters may be due to not every community college having full coverage of every lower division course for many popular majors at UCs (e.g. computer science is often difficult to find full coverage for, due to variation in UC lower division computer science courses), so transfer students in these majors have to “catch up” after transfer.