LAS Controller elected to circle an aircraft to other than the principal runway due to an overtake situation and violating airspace in the process; the reporter noting the Final Controllers need to compensate for compression.

Narrative

While working Local Control 1; I noticed aircraft on final were slowing rather quickly due to the high winds. I already had 2 aircraft with 2 miles of separation behind each other on final; but speeds were matched. A B737 started making his turn to final doing 180 KTS. He joined final about 2.5 miles behind another B737 doing 140 knots. On initial contact; I advised the B737 that he had a 40 KT overtake on the B737 ahead; he replied that he was slowing. Separation started diminishing down to less than 2 miles and I noted that the B737 was still doing 180 KTS. With another aircraft about 2.5 miles behind him; I had only 2 options; circle the B737 to the 19's or send him around. I asked the B737 if he could accept 19L or 19R; he replied affirmative. I immediately circled the B737 to 19L without coordinating with the Approach Controller. I violated another Controller's airspace without coordination or a point-out before conducting the circle. The Supervisor asked me if I had pointed the aircraft out; and I said negative; can you call them. The Supervisor called the TRACON to advise them of the maneuver. With separation decreasing and the short amount of time I had to react; I did what I felt I needed to do to separate airplanes even if it meant an airspace violation. The B737 landed safely without incident. Even though the pilot was told to follow the preceding aircraft; the TRACON needs to understand that; especially in high winds; they can't compress our final to the minimums. There were 4 aircraft in a 7 mile space; someone was going to have to go around.