Is it time to move on from shared hosting?

[ZomgStuff]

So I can't tell if bluehost.com has some really outdated hardware, or am I really causing them server performance issues. Basically they said if I cause them problems one more time they're permanently suspending my account. I've apparently running a lot of slow SQL queries.

A little information about my site
URL: http://forum.zomgstuff.net/
Total Threads: 16,353
Total Posts: 160,968
Total Members: 9,477
Average Daily Unique Members: ~105
Data Usage: 128.15 MB
Index Usage: 51.23 MB
Size of database SQL backup: ~135mb

I also have quite a bit of plugins as well.

Server average load times used to be 2-4 seconds, but after I forced guests to register to view thread contents, it's currently 1.3 seconds.

I've looked at the sql_sloq_queries log in my hosting and I see dozens of daily entries. Most of them say the "slow" script ran for an average of 3-4 seconds.

Here's a couple of examples of slow queries.

# Fri Nov 28 13:19:35 2008
# Query_time: 2  Lock_time: 0  Rows_sent: 4  Rows_examined: 32
use zomgstu1_theforums;
SELECT
  post.*, post.username AS postusername, post.ipaddress AS ip, IF(post.visible = 2, 1, 0) AS isdeleted,
  user.*, userfield.*, usertextfield.*,
  icon.title as icontitle, icon.iconpath,
  avatar.avatarpath, NOT ISNULL(customavatar.userid) AS hascustomavatar, customavatar.dateline AS avatardateline,customavatar.width AS avwidth,customavatar.height AS avheight,
  spamlog.postid AS spamlog_postid,
  deletionlog.userid AS del_userid, deletionlog.username AS del_username, deletionlog.reason AS del_reason,
  editlog.userid AS edit_userid, editlog.username AS edit_username, editlog.dateline AS edit_dateline,
  editlog.reason AS edit_reason, editlog.hashistory,
  postparsed.pagetext_html, postparsed.hasimages,
  sigparsed.signatureparsed, sigparsed.hasimages AS sighasimages,
  sigpic.userid AS sigpic, sigpic.dateline AS sigpicdateline, sigpic.width AS sigpicwidth, sigpic.height AS sigpicheight,
  IF(displaygroupid=0, user.usergroupid, displaygroupid) AS displaygroupid, infractiongroupid
		FROM post AS post
		LEFT JOIN user AS user ON(user.userid = post.userid)
		LEFT JOIN userfield AS userfield ON(userfield.userid = user.userid)
		LEFT JOIN usertextfield AS usertextfield ON(usertextfield.userid = user.userid)
		LEFT JOIN icon AS icon ON(icon.iconid = post.iconid)
		LEFT JOIN avatar AS avatar ON(avatar.avatarid = user.avatarid) LEFT JOIN customavatar AS customavatar ON(customavatar.userid = user.userid)
		LEFT JOIN spamlog AS spamlog ON(spamlog.postid = post.postid)
  LEFT JOIN deletionlog AS deletionlog ON(post.postid = deletionlog.primaryid AND deletionlog.type = 'post')
		LEFT JOIN editlog AS editlog ON(editlog.postid = post.postid)
		LEFT JOIN postparsed AS postparsed ON(postparsed.postid = post.postid AND postparsed.styleid = 72 AND postparsed.languageid = 1)
		LEFT JOIN sigparsed AS sigparsed ON(sigparsed.userid = user.userid AND sigparsed.styleid = 72 AND sigparsed.languageid = 1)
		LEFT JOIN sigpic AS sigpic ON(sigpic.userid = post.userid)
		WHERE post.postid IN (0,168362,168390,168583,168584)
		ORDER BY post.dateline

# Sat Nov 29 20:35:29 2008
# Query_time: 6  Lock_time: 0  Rows_sent: 1000  Rows_examined: 14889
use zomgstu1_theforums;
SELECT postid
  FROM post AS post
  INNER JOIN thread AS thread ON(thread.threadid = post.threadid)
  WHERE post.userid = 1
  AND thread.forumid IN(104,2,90,102,131,12,429,430,426,69,431,18,44,432,132)
  ORDER BY post.dateline DESC
  LIMIT 1000

# Sat Nov 29 20:59:22 2008
# Query_time: 3  Lock_time: 0  Rows_sent: 4958  Rows_examined: 4958
use zomgstu1_theforums;
SELECT postid, wordid,
  CASE intitle
  WHEN 0 THEN score
  WHEN 1 THEN score + 5
  WHEN 2 THEN score + 5 + 5
  ELSE score
  END AS score
		FROM postindex
		WHERE wordid IN (0,1126,2261,5755)

Basically do you think I've outgrown shared hosting, or do I just need to make my scripts more efficient and optimize them?