mod_perl/dbi/apache query will not finish

I've been experiencing this problem ever since upgrading from RedHat 7.3
to 8.0, which included a Postgresql upgrde to version 7.2.2.

I send a query to the Postgres backend using a mod_perl script and DBI.
I watch the trace log, it looks something like this:

dbd_st_execute: statement = >SELECT CITY_ID, CITY_NAME
FROM LOCAL_INFO_CITIES
WHERE STATE_ID = '5'
AND ( PROVISIONAL_IND <> 'P' OR CITY_ID = 0 )
ORDER BY CITY_NAME
<
<- execute= 76 at create_local_info_2.pl line 61
-> bind_columns for DBD::Pg::st (DBI::st=HASH(0x82c6ad4)~0x82e7df8 undef SCALAR(0x82a0e68) SCALAR(0x82a0e80)) thr#804b3c0
<- bind_columns= 1 at create_local_info_2.pl line 62
-> fetch for DBD::Pg::st (DBI::st=HASH(0x82c6ad4)~0x82e7df8) thr#804b3c0
dbd_st_fetch
<- fetch= [ '10040' 'Agoura Hills' ] row1 at create_local_info_2.pl line 63
-> fetch for DBD::Pg::st (DBI::st=HASH(0x82c6ad4)~0x82e7df8) thr#804b3c0
dbd_st_fetch
<- fetch= [ '10019' 'All Cities' ] row2 at create_local_info_2.pl line 63
-> fetch for DBD::Pg::st (DBI::st=HASH(0x82c6ad4)~0x82e7df8) thr#804b3c0
dbd_st_fetch
<- fetch= [ '752' 'Auberry' ] row3 at create_local_info_2.pl line 63

...

<- fetch= [ '564' 'Irvine' ] row27 at create_local_info_2.pl line 63
-> fetch for DBD::Pg::st (DBI::st=HASH(0x82c6ad4)~0x82e7df8) thr#804b3c0
dbd_st_fetch
<- fetch= [ '244' 'Lake Elsinore' ] row28 at create_local_info_2.pl line 63

And that's it. I can see that it wants to return 76 rows, but it stops at row28. Sometimes, several minutes later, it does return the remaining rows, but by then the browser has given up.

Queries returning, say, only 25 rows work beautifully.

The processor load is light. Here's a partial output from a "top" command:

5:00am up 11 days, 17 min, 1 user, load average: 0.16, 0.42, 0.31
150 processes: 147 sleeping, 2 running, 1 zombie, 0 stopped
CPU states: 1.1% user, 2.6% system, 0.0% nice, 1.3% idle
Mem: 384680K av, 375728K used, 8952K free, 0K shrd, 26500K buff
Swap: 787176K av, 106680K used, 680496K free 242228K cached

PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND
31788 matching 15 0 1072 1072 780 R 6.5 0.2 0:00 top
28681 powerpul 15 0 22964 17M 13232 S 0.9 4.5 1:44 galeon-bin
1 root 15 0 472 436 424 S 0.0 0.1 0:05 init

$ uname -a
Linux abigail 2.4.18-19.8.0 #1 Thu Dec 12 04:37:40 EST 2002 i686 athlon i386 GNU/Linux