Re: High cpu usage after many inserts

Taken after 9000 rows entered, by this stage performance is terrible.
           relation            |  size 
-------------------------------+--------
 public.mdl_log                | 597 MB
 public.mdl_forum_posts        | 389 MB
 public.mdl_log_coumodact_ix   | 198 MB
 public.mdl_user               | 193 MB
 public.mdl_cache_text         | 162 MB
 public.mdl_log_usecou_ix      | 137 MB
 public.mdl_log_act_ix         | 119 MB
 public.mdl_log_cmi_ix         | 98 MB
 public.mdl_log_tim_ix         | 97 MB
 public.mdl_log_id_pk          | 97 MB
 public.mdl_question_states    | 48 MB
 public.mdl_stats_user_daily   | 48 MB
 public.mdl_hotpot_responses   | 47 MB
 public.mdl_register_downloads | 45 MB
 public.mdl_message_read       | 37 MB
 public.mdl_course_display     | 37 MB
 public.mdl_stats_user_weekly  | 31 MB
 public.mdl_mnet_log           | 27 MB
 public.mdl_user_ema_ix        | 26 MB
 public.mdl_regidown_url_ix    | 23 MB
(20 rows)



as you can see, the tables arent growing by much (only a few mb) so is this really to do with buffer/cache size?
I set shared_buffers to 3072 (from 2048) and it hasnt made much improvement, requests are still taking longer and longer to execute.