B737-800 FLT CREW EXPRESSED FRUSTRATION WITH ALT AND SPD RESTR INBOUND TO SFO.

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ACFT X WAS ON THE MODESTO 2 ARR INTO SFO. WE WERE APPROX 20 NM E OF CEDES INTXN AT FL240. ZOA TOLD US TO CROSS CEDES INTXN AT 11000 FT AND MAINTAIN 300 KTS OR BETTER. WE WERE NOT ABLE TO MAKE CEDES INTXN XING ALT BECAUSE OF THE ALT WE HAD TO LOSE AND THE AIRSPD CONSTRAINT OF 300 KTS OR GREATER. APCHING CEDES INTXN WE ADVISED ZOA WE WERE NOT GOING TO BE ABLE TO MAKE THE ALT RESTR AT CEDES INTXN. SHORTLY BEFORE REACHING CEDES INTXN; ZOA CLRED US TO 7000 FT. ATC HAS TO PLAN BETTER AND UNDERSTAND IT IS IMPOSSIBLE TO MEET BOTH ALT AND AIRSPD IN SUCH A SHORT DISTANCE WITH A B737-800 ACFT. ESPECIALLY WITH A SPD RESTR AS WE WERE UNABLE TO UTILIZE SPD BRAKES TO GET DOWN BECAUSE OF AN ACFT AIRSPD LIMITATION. BECAUSE OF ALL OF THIS WE ENDED UP WAY TOO HIGH FOR THE APCH TO RWY 28R AND THEN AT THE LAST MIN THEY SWITCHED US TO RWY 28L AND WE HAD TO EXECUTE A MISSED APCH AND COME BACK AND LAND. TRYING TO PROGRAM AND REPROGRAM THE FMC; FLY THE AIRPLANE; GO DOWN AND SLOW DOWN AND WATCH FOR TFC GETS TO BE AN ENORMOUS WORKLOAD FOR US AT A CRITICAL TIME. FORTUNATELY THERE WERE NO CONFLICTS WITH OTHER ACFT THIS TIME.