squid-1.1.beta13 slowing

I'm started to run squid-1.1.beta13 yesterday with clean cache
and it worked fine yesterday:
% zcat access.log.0.gz | nawk -f access-times.awk
        local cached remote cached remote proxied no proxy,cache other
Nummer: 114132 0 0 253682 28270
         28.8% 0.0% 0.0% 64.0% 7.1%
Zeit: 0.8s 0.0s 0.0s 4.3s 16.3s

But today squid uses all CPU (233 MHz alpha) and doesn't work so fast:
(not a full day stats)
        local cached remote cached remote proxied no proxy,cache other
Nummer: 65966 0 0 114561 12878
         34.1% 0.0% 0.0% 59.2% 6.7%
Zeit: 2.0s 0.0s 0.0s 5.7s 16.2s

There is enough (256MB) memory: squid uses 100MB.

What should I do? Do sources have some hashtable settings, which are too small
or what does store_objects_per_bucket mean in squid.conf?

-- 
Pekka Järveläinen                       Tel. +358 9  457 2467
Centre for Scientific Computing/FUNET   GSM  +358 40 543 7856
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02101 ESPOO, FINLAND			jarvelai@csc.fi