Deleting aggregator feed or all items results in insanely long delete sql statement

Logging slow queries results in a sql statement along the lines of:

DELETE FROM aggregator_category_item WHERE iid = 3738 OR iid = 3739 OR iid = 3740 OR iid = 3741 OR iid = 3742 OR iid = 3743 OR iid = 3744 OR iid = 3745 OR iid = 3746 OR iid = 3747 OR iid = 3748 OR iid = 3749 OR iid = 3750 OR iid = 3751 OR iid = 3752 OR iid = 3768 OR iid = 3769 OR iid = 3770 OR iid = 3771 OR iid = 3772 OR iid = 3773 OR iid = 3774 OR iid = 3775 OR iid = 3776 OR iid = 3777 OR iid = 3778 OR iid = 3779 OR iid = 3780 OR iid = 3781 OR iid = 3782 OR iid = 3798 OR iid = 3799 OR iid = 3800 OR iid = 3801 OR iid = 3802 OR iid = 3803 OR iid = 3804 OR iid = 3805 OR iid = 3806 OR iid = 3807 OR iid = 3808 OR iid = 3809 OR iid = 3810 OR iid = 3811 OR iid = 3812 OR iid = 3828 OR iid = 3829 OR iid = 3830 OR iid = 3831 OR iid = 3832 OR iid = 3833 OR iid = 3834 OR iid = 3835 OR iid = 3836 OR iid = 3837 OR iid = 3838 OR iid = 3839 OR iid = 3840 OR iid = 3841 OR iid = 3842 OR iid = 3858 OR iid = 3859 OR iid = 3860 OR iid = 3861 OR iid = 3862 OR iid = 3863 OR iid = 3864 OR iid = 3865 OR iid = 3866 OR iid = 3867 OR iid = 3868 OR iid = 3869 OR iid = 3870 OR iid = 3871 OR iid = 3872 OR iid = 3888 OR iid = 3889 OR iid = 3890 OR iid = 3891 OR iid = 3892 OR iid = 3893 OR iid = 3894 OR iid = 3895 OR iid = 3896 OR iid = 3897 OR iid = 3898 OR iid = 3899 OR iid = 3900 OR iid = 3901 OR iid = 3902 OR iid = 3918 OR iid = 3919 OR iid = 3920 OR iid = 3921 OR iid = 3922 OR iid = 3923 OR iid = 3924 OR iid = 3925 OR iid = 3926 OR iid = 3927 OR iid = 3928 OR iid = 3929 OR iid = 3930 OR iid = 3931 OR iid = 3932 OR iid = 3948 OR iid = 3949 OR iid = 3950 OR iid = 3951 OR iid = 3952 OR iid = 3953 OR iid = 3954 OR iid = 3955 OR iid = 3956 OR iid = 3957 OR iid = 3958 OR iid = 3959 OR iid = 3960 OR iid = 3961 OR iid = 3962 OR iid = 3978 OR iid = 3979 OR iid = 3980 OR iid = 3981 OR iid = 3982 OR iid = 3983 OR iid = 3984 OR iid = 3985 OR iid = 3986 OR iid = 3987 OR iid = 3988 OR iid = 3989 OR iid = 3990 OR iid = 3991 OR iid = 3992 OR iid = 4008 OR iid = 4009 OR iid = 4010 OR iid = 4011 OR iid = 4012 OR iid = 4013 OR iid = 4014 OR iid = 4015 OR iid = 4016 OR iid = 4017 OR iid = 4018 OR iid = 4019 OR iid = 4020 OR iid = 4021 OR iid = 4022 OR iid = 4038 OR iid = 4039 OR iid = 4040 OR iid = 4041 OR iid = 4042 OR iid = 4043 OR iid = 4044 OR iid = 4045 OR iid = 4046 OR iid = 4047 OR iid = 4048 OR iid = 4049 OR iid = 4050 OR iid = 4051 OR iid = 4052 OR iid = 4068 OR iid = 4069 OR iid = 4070 OR iid = 4071 OR iid = 4072 OR iid = 4073 OR iid = 4074 OR iid = 4075 OR iid = 4076 OR iid = 4077 OR iid = 4078 OR iid = 4079 OR iid = 4080 OR iid = 4081 OR iid = 4082 OR iid = 4098 OR iid = 4099 OR iid =....

It goes on much longer, causing the PHP script to time out and locking the MySQL database for 5 minutes.