Query cause 100% CPU

Actually i'm not sure what to do here. I'm using shared hosting and just received message from hoster that my MySql code, actually each query make 100% CPU. Thus if there are 3 queries then it is 300% CPU. Strange.

Code that i used is well optimized for fast performance:

Code:

$query=" SELECT DISTINCT ip FROM visits AS r1
JOIN (SELECT ROUND(
  RAND( ) * (
    SELECT MAX( id ) FROM visits)
  ) AS id
) AS r2
WHERE r1.id >= r2.id
AND counter='1'
ORDER BY r1.id DESC
LIMIT 10";
$result=mysql_query($query);
while($row =mysql_fetch_array($result)){
$ip=$row['ip'];

echo "$ip,";

Another piece of code is almost similar:

Code:

$query=" SELECT DISTINCT ip FROM visits AS r1
JOIN (SELECT ROUND(
  RAND( ) * (
    SELECT MAX( id ) FROM visits)
  ) AS id
) AS r2
WHERE r1.id >= r2.id
AND ip REGEXP '[A-Za-z0-9]' AND ip NOT REGEXP '\\([^\\)]*www.*\\)'
ORDER BY r1.id ASC
LIMIT 8";
$result=mysql_query($query);
while($row =mysql_fetch_array($result)){

$ip=$row['ip'];
 
echo "$ip,";

Is there anything wrong with code?
btw

Table is very big. There are 176.000 rows as it means anything.

Thanks for any input.

IT is MySql.

Use the below query to find out the query which uses maximum resources and time

SELECT TOP 20
qs.sql_handle,
qs.execution_count,
qs.total_worker_time AS Total_CPU,
total_CPU_inSeconds = --Converted from microseconds
qs.total_worker_time/1000000,
average_CPU_inSeconds = --Converted from microseconds
(qs.total_worker_time/1000000) / qs.execution_count,
qs.total_elapsed_time,
total_elapsed_time_inSeconds = --Converted from microseconds
qs.total_elapsed_time/1000000,
st.text,
qp.query_plan
from
sys.dm_exec_query_stats as qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) as st
cross apply sys.dm_exec_query_plan (qs.plan_handle) as qp
ORDER BY qs.total_worker_time desc