map take long time to update

edit

hi i am using gmapping to build map and i did and its accurate , but while i am building the map some time there is places did not be added to map while updating, and the map update take a lot of time there is no problem with my odometery if i move my robot 1m forward it goes 1m without any problem if i turn it 90 deg it turn without any problem. i am using the encoder do determine just forward and backward (linear motion) and gyro for angular motion.

my question is: 1- Is there any way to fast the update of map? its not instantaneous it may rotate about it self for 3 time and alway update just the first position, this occur if the space is small and there is a lot of object. 2- how i can make the laser scan update every thing around him without any thing be missed.(no unknown zone). 3- I hope that some one can explain the (map_update_interval )parameter and (Particles) parameter . 4- i have this error:

Scan Matching Failed, using odometry. Likelihood=-4266.67
lp:0.303589 0.000376325 0.0261353

but it know after i make minimum score parameter = 10000 it not effect the map but still happening , but no over lab or jump occur. i wana ask if this cause a problem for updating the map.

last thing here the gmapping parameter i hope any one can help:

<!--remap from="scan" to="base_scan"/-->
<param name="base_frame" value="/base_link" />
<param name="odom_frame" value="/odom" />
<param name="map_update_interval" value="5.0"/>
<param name="maxUrange" value="4.5"/>
<!--param name="maxRange" value="4.0"/-->
<param name="sigma" value="0.05"/>
<param name="kernelSize" value="1"/>
<param name="lstep" value="0.05"/>
<param name="astep" value="0.05"/>
<param name="iterations" value="5"/>
<param name="lsigma" value="0.075"/>
<param name="ogain" value="3.0"/>
<param name="lskip" value="0"/>
<param name="minimumScore" value="10000"/>
<param name="srr" value="0.01"/>
<param name="srt" value="0.02"/>
<param name="str" value="0.01"/>
<param name="stt" value="0.02"/>
<param name="linearUpdate" value="0.40"/>
<param name="angularUpdate" value="0.40"/>
<param name="temporalUpdate" value="-1.0"/>
<param name="resampleThreshold" value="0.5"/>
<param name="particles" value="80"/>
<param name="xmin" value="-50.0"/>
<param name="ymin" value="-50.0"/>
<param name="xmax" value="50.0"/>
<param name="ymax" value="50.0"/>
<param name="delta" value="0.05"/>
<param name="llsamplerange" value="0.01"/>
<param name="llsamplestep" value="0.01"/>
<param name="lasamplerange" value="0.005"/>
<param name="lasamplestep" value="0.005"/>
<param name="transform_publish_period" value="0.1"/>

edit: just for the information i can move the robot from point a to b without any problem in the map so the odometer is not wrong. thanks.