Proteases are enzymes that use water to break amide bonds in protein substrates. This process, proteolysis, plays a large number of functions, from digestion to cell signaling, and the regulation of protease functions is fundamental for all life forms. A fascinating clbad of proteases has its active sites soaked in water immersed in the water-repellent (hydrophobic) environment of the lipid bilayer and cleaves the transmembrane regions of its substrates. How are these intramembrane cleavage proteases (I-CLiPs) (one) Carrying out this seemingly paradoxical process has intrigued biochemists for 20 years. Among the challenges is deciphering how I-CLiPs diffuse through viscous cell membranes packed with other membrane proteins to find their substrates. On page 497 of this issue, Kreutzberger. et al. (two) find that a clbad of I-CLiPs, the rhomboidal family, diffuses much faster than other membrane proteins, in violation of the estimated speed limits for their size. This implies that these membrane proteins have evolved for rapid diffusion to carry out their functions effectively.