selects on sysmaster are very slow

Dear list, since 3 or 4 weeks selects on sysmaster esp. systabnames behave very, very slow. A simple select: select * from systabnames into temp t1 with no log; last ca. 30 minutes and finds 14455 rows. The waitstaits says that the session is in aiowait most of the time. In version 9.40.FC4W2 systabnames is a table, not a view. Output from ksh ratios_ask.ksh: IBM Informix Dynamic Server Version 9.40.FC4W2 -- On-Line -- Up 7 days 20:08:39 -- 7083008 Kbytes Profile dskreads pagreads bufreads %cached dskwrits pagwrits bufwrits %cached 1224420288 3162640766 66361010949 98.15 134853118 502422323 795403015 83.05 isamtot open start read write rewrite delete commit rollbk 51460834765 1594164197 2303970025 35360654715 105201097 95559524 55606879 33874410 289209 gp_read gp_write gp_rewrt gp_del gp_alloc gp_free gp_curs 688 0 2266 0 0 0 0 ovlock ovuserthread ovbuff usercpu syscpu numckpts flushes 0 0 0 2241759.39 648669.24 1924 5191 bufwaits lokwaits lockreqs deadlks dltouts ckpwaits compress seqscans 83022572 98883 24473429111 0 0 68575 35551085 26356273 ixda-RA idx-RA da-RA RA-pgsused lchwaits 323612202 16547970 524321144 864155483 260127699 ReadAhead Utilization (UR): 99.9623 % Bufwaits Ratio(BR): 2.09757 % -n Average Buffer Turnover Rate (BTR): 19.6773/HR Stats reset 95:47:05 ago. Server: SunOS 5.9 Generic_117171-12 sun4u sparc SUNW,Netra-T12 What may cause that behaviour and can it grow to a bigger problem? Reinhard.