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   1  Phorum 5 performance notes
   2  ==========================
   3  
   4  Several of Phorum's options have a tradeoff effect: enabling more 
   5  features can slow Phorum down. This document describes which options 
   6  these are and tries to explain the performance cost of each one.
   7  
   8  Which options you should turn off to improve performance depends 
   9  on the way you use your Phorum installation.
  10  
  11  Table of contents:
  12  
  13  1. Global Settings
  14     1.1 DNS Lookups
  15     1.2 Count New Private Messages
  16     1.3 Enable Moderator Notifications
  17     1.4 Track User Usage
  18     1.5 Show New Count in Forum List
  19  2. Forum Settings
  20     2.1 Email Messages to Moderators
  21     2.2 Allow Email Notification
  22     2.3 Count Views
  23     2.4 Show New Count in Forum List
  24     2.5 Ban List
  25     2.6 Censor List
  26     2.7 Move Threads on Reply
  27     2.8 Check for duplicates
  28  
  29  
  30  1. Global Settings
  31  -------------------------------------------------------------------------------
  32  
  33  
  34   1.1 DNS Lookups
  35   ---------------
  36  
  37      DNS lookups cause Phorum to display DNS entries (hostnames) instead
  38      of IP addresses on posts. It also will enable checking if mail
  39      addresses point to valid domains.
  40  
  41      On a forum with a lot of posts, enabling this will result in a
  42      significant number of queries to your DNS server. Phorum's performance
  43      will slow down while a query is running, as it will wait for the result
  44      of the query.
  45  
  46      If your DNS server is slow, this may give the impression to your users
  47      that posting a message is very slow. If that is the case, you should
  48      turn DNS lookups off. If you have access to a fast DNS server or only
  49      have a few regular posters, you should be able to leave it on.
  50  
  51  
  52   1.2 Count New Private Messages
  53   ------------------------------
  54  
  55      If enabled, this option will alert users when they have new private
  56      messages. On every page a logged in user visits, Phorum will check
  57      to see if they have new private messages.
  58  
  59      If you have a large number of active users at one time with a large
  60      number of private messages, this query can start to slow down your
  61      database. Turning it off may help performance, but will also remove
  62      the notification users get when they receive a new private message.
  63      You can also enable userdata caching under "Cache Settings" to
  64      improve performance.
  65  
  66  
  67   1.3 Enable Moderator Notifications
  68   ----------------------------------
  69  
  70      Similar to the Count New Private Messages option, this option will
  71      alert users who are also moderators when they have a new item that
  72      requires their attention.
  73  
  74      The performance hit of this feature is basically nothing for users
  75      without moderator permissions, as Phorum will never perform the checks.
  76      Moderators will suffer a small performance hit, depending on what type
  77      of moderator they are.
  78  
  79      Administrators will suffer a larger performance hit, as they are
  80      effectively moderators of every type, so all of the checks will be
  81      performed.
  82  
  83  
  84   1.4 Track User Usage
  85   --------------------
  86  
  87      This option controls how often Phorum will record when a user was last
  88      active. Setting this to be more frequent results in more accurate last
  89      activity data, but also causes more database writes.
  90  
  91      The "Constantly" setting will record the users activity on every page
  92      hit by any logged in user, resulting in a dramatic increase in the number
  93      of database writes. In most databases, a write is much slower then a
  94      read, so this can dramatically reduce performance. This setting is not
  95      recommended, except for installations with very few users, or very
  96      powerful hardware.
  97  
  98      If you are using a module that actively requires this data (such as the
  99      Online Users module), the setting "Once per 5 minutes" is the best
 100      setting, as the data will be too out of date if you update the data
 101      less frequently.
 102  
 103      If you are not using such a module, "Once per day" or "Once per hour" are
 104      highly recommended over the other options. "Never" disables this function
 105      entirely, and is recommended if you simply don't care to know if a user
 106      is active or not.
 107  
 108      Note: the option "Cache User Data" should be disabled if you have this
 109      feature set to "Once per 5 minutes" or "Constantly", as the caching
 110      will not be of much use.
 111  
 112      
 113   1.5 Show New Count in Forum List
 114   --------------------------------
 115   
 116      If you have a large number of posts, a large number of forums, a large 
 117      number of users or some combination of the three, this setting could cause
 118      some issues.  If you want to try and keep the feature, you can adjust the
 119      constant PHORUM_MAX_NEW_INFO to something lower than 1000 in 
 120      include/constants.php.  Setting this too low however will make messages not
 121      show as unread even though they have not been read by the user.
 122      
 123  
 124  2. Forum Settings
 125  -------------------------------------------------------------------------------
 126  
 127  
 128   2.1 Email Messages to Moderators
 129   --------------------------------
 130  
 131      If enabled, every post in the forum will be emailed to the forum's
 132      moderators. Administrators are automatically moderators in every forum,
 133      and will also get the emails.
 134  
 135      This option should not directly affect Phorum's performance, but when
 136      a post is made, it will cause some emails to be created. If you have a
 137      large number of moderators and a lot of posts being made by users, this
 138      can generate a significant amount of email traffic.
 139  
 140      The traffic should only be a problem on very large forums or if you have
 141      a slow mail server. In other cases, it should not cause significant
 142      performance issues.
 143  
 144  
 145   2.2 Allow Email Notification
 146   ----------------------------
 147  
 148      This option has similar issues to the Email Messages to Moderators 
 149      setting, except the recipients of the emails are users who have
 150      selected the option to have replies in a followed thread emailed to
 151      them.
 152  
 153      If a large number of users is using this feature in a busy thread, it
 154      can affect performance. If only few users are using this feature, it 
 155      will not cause significant performance issues.
 156  
 157  
 158   2.3 Count Views
 159   ---------------
 160      
 161      If enabled, this feature records the number of views each post gets.
 162      For every post read, the counter will be incremented in the database.
 163      On a busy forum, this will result in a tremendous number of database
 164      writes, dramatically slowing down performance.
 165  
 166      Enabling this feature is not recommended for high traffic forums,
 167      unless you have very powerful hardware.
 168  
 169  
 170   2.4 Show New Count in Forum List
 171   --------------------------------
 172  
 173      If enabled, the count of new messages for each forum will appear in
 174      index.php. While quite handy, this has to run several queries per
 175      listed forum. If there are many forums on the index.php page, there
 176      could be a significant performance hit.  
 177  
 178      
 179   2.5 Ban List
 180   ------------
 181  
 182      The ban list is a list of words that are banned when posting a message.
 183      There is a small performance penalty for searching for the banned words,
 184      but only when posting.
 185  
 186  
 187   2.6 Censor List
 188   ---------------
 189  
 190      The censor list is a list of filtered words, that is checked on every
 191      post read. Because it is checked far more often than the ban list, a
 192      large censor list will affect performance much more.
 193  
 194  
 195   2.7 Move Threads on Reply
 196   -------------------------
 197  
 198      "Move Threads on Reply" means that a thread which gets a new reply causes
 199      the topic to be moved to the top of the forum, hence the topics are
 200      sorted by their last reply and not by their first post in the message
 201      list.
 202  
 203      In Flat-mode there is no performance hit. In Threaded-mode it causes
 204      a large overhead because of the complexity of the sorting and the
 205      counting of posts on a page.
 206  
 207  
 208   2.8 Check for duplicates
 209   ------------------------
 210     
 211      "Check for duplicates" runs one additional query while posting to check
 212      if that post has been made before. That query should be fast and just
 213      a small overhead.
 214