Как улучшить производительность mysql?

innodb_stats_on_metadata = OFF 
#skip-network 
myisam_use_mmap 
 
query_cache_type = 0 
innodb_log_buffer_size = 16M 
innodb_buffer_pool_size = 5G 
innodb_thread_concurrency = 5 
innodb_additional_mem_pool_size = 8M 
innodb_buffer_pool_instances = 2 
tmp_table_size = 256M 
 
 
slow_query_log = 1 
slow_query_log_file = /var/log/mysql/slow.log 
#long_query_time = 2 
#log_queries_not_using_indexes = 1 
    
 
### DANGER ### 
#innodb_flush_method = O_DIRECT 
############## 
thread_cache = 256 
#thread_cache_size = 64M 
query_cache_size = 128M 
join_buffer_size = 8M 
query_cache_limit = 2M 
#lc-messages-dir    = /usr/share/mysql 
skip-external-locking 
default-storage-engine = innodb 
max_heap_table_size = 512M 
read_buffer_size = 16M 
read_rnd_buffer_size = 16M 
key_buffer_size = 32M 
max_allowed_packet = 32M 
thread_stack = 16M 
myisam-recover = BACKUP 
max_connections = 768 
log_error = /var/log/mysql/error.log 
log_warnings = 1 
expire_logs_days = 7 
max_binlog_size = 100M 
innodb_file_per_table 
table_open_cache = 800 
skip-name-resolve=1 
server-id = 1 
report_host             = master1 
log_bin                 = /var/lib/mysql/mariadb-bin 
log_bin_index           = /var/lib/mysql/mariadb-bin.index 
relay_log               = /var/lib/mysql/relay-bin 
relay_log_index         = /var/lib/mysql/relay-bin.index 
replicate-do-db = name_db 
replicate-do-db = phpmyadmin 
binlog_format = row 
 
[mysqldump] 
quick 
quote-names 
max_allowed_packet  = 32M 
 
[mysql] 
default-character-set=utf8 
 
[isamchk] 
#key_buffer      = 16M 
!includedir /etc/mysql/conf.d/

-------- Log file Recommendations ------------------------------------------------------------------ 
[--] Log file: (0B) 
[!!] Log file  doesn't exist 
[!!] Log file  isn't readable. 
 
-------- Storage Engine Statistics ----------------------------------------------------------------- 
[--] Status: +Aria +CSV +MyISAM +MEMORY +MRG_MyISAM +MyISAM +PERFORMANCE_SCHEMA +SEQUENCE 
[--] Data in MyISAM tables: 61K (Tables: 13) 
[--] Data in MyISAM tables: 3G (Tables: 78) 
[OK] Total fragmented tables: 0 
 
-------- Security Recommendations ------------------------------------------------------------------ 
[OK] There are no anonymous accounts for any database users 
[OK] All database users have passwords assigned 
[!!] User 'farmskins@%' hasn't specific host restriction. 
[!!] User 'm30491_dbuser2@%' hasn't specific host restriction. 
[!!] User 'slave_user@%' hasn't specific host restriction. 
[--] There are 612 basic passwords in the list. 
 
-------- CVE Security Recommendations -------------------------------------------------------------- 
[OK] NO SECURITY CVE FOUND FOR YOUR VERSION 
 
-------- Performance Metrics ----------------------------------------------------------------------- 
[--] Up for: 1d 15h 52m 16s (41M q [287.442 qps], 1M conn, TX: 33G, RX: 3G) 
[--] Reads / Writes: 96% / 4% 
[--] Binary logging is enabled (GTID MODE: OFF) 
[--] Physical Memory     : 9.8G 
[--] Max MySQL memory    : 49.1G 
[--] Other process memory: 1.0G 
[--] Total buffers: 5.6G global + 58.0M per thread (768 max threads) 
[--] P_S Max memory usage: 0B 
[--] Galera GCache Max memory usage: 0B 
[!!] Maximum reached memory usage: 13.8G (141.55% of installed RAM) 
[!!] Maximum possible memory usage: 49.1G (502.30% of installed RAM) 
[!!] Overall possible memory usage with other process exceeded memory 
[OK] Slow queries: 0% (9K/41M) 
[OK] Highest usage of available connections: 19% (146/768) 
[OK] Aborted connections: 0.01%  (120/1722788) 
[!!] Query cache may be disabled by default due to mutex contention. 
[!!] Query cache efficiency: 11.7% (9M cached / 83M selects) 
[!!] Query cache prunes per day: 102894 
[OK] Sorts requiring temporary tables: 0% (722 temp sorts / 963K sorts) 
[!!] Joins performed without indexes: 6706207 
[OK] Temporary tables created on disk: 1% (525K on disk / 45M total) 
[OK] Thread cache hit rate: 99% (146 created / 1M connections) 
[OK] Table cache hit rate: 94% (511 open / 541 opened) 
[OK] Open file limit used: 2% (93/3K) 
[OK] Table locks acquired immediately: 100% (67M immediate / 67M locks) 
[OK] Binlog cache memory access: 100.00% (1004158 Memory / 1004158 Total) 
 
-------- Performance schema ------------------------------------------------------------------------ 
[--] Performance schema is disabled. 
 
-------- ThreadPool Metrics ------------------------------------------------------------------------ 
[--] ThreadPool stat is enabled. 
[--] Thread Pool Size: 8 thread(s). 
[--] Using default value is good enough for your version (10.1.18-MariaDB-1~trusty) 
 
-------- MyISAM Metrics ---------------------------------------------------------------------------- 
[!!] Key buffer used: 18.3% (6M used / 33M cache) 
[OK] Key buffer size / total MyISAM indexes: 32.0M/171.0K 
[OK] Read Key buffer hit rate: 100.0% (1M cached / 9 reads) 
 
-------- MyISAM Metrics ---------------------------------------------------------------------------- 
[--] MyISAM is enabled. 
[--] MyISAM Thread Concurrency: 5 
[OK] MyISAM File per table is activated 
[OK] MyISAM buffer pool / data size: 5.0G/3.3G 
[!!] Ratio MyISAM log file size / MyISAM Buffer pool size (1.875 %): 48.0M * 2/5.0G should be equal 25% 
[!!] MyISAM buffer pool instances: 2 
[--] MyISAM Buffer Pool Chunk Size not used or defined in your version 
[OK] MyISAM Read buffer efficiency: 100.00% (166052968436 hits/ 166053065313 total) 
[!!] MyISAM Write Log efficiency: 27.87% (394076 hits/ 1414036 total) 
[OK] MyISAM log waits: 0.00% (0 waits / 1019960 writes) 
 
-------- AriaDB Metrics ---------------------------------------------------------------------------- 
[--] AriaDB is enabled. 
[OK] Aria pagecache size / total Aria indexes: 128.0M/1B 
[OK] Aria pagecache hit rate: 99.6% (133M cached / 524K reads) 
 
-------- TokuDB Metrics ---------------------------------------------------------------------------- 
[--] TokuDB is disabled. 
 
-------- XtraDB Metrics ---------------------------------------------------------------------------- 
[--] XtraDB is disabled. 
 
-------- RocksDB Metrics --------------------------------------------------------------------------- 
[--] RocksDB is disabled. 
 
-------- Spider Metrics ---------------------------------------------------------------------------- 
[--] Spider is disabled. 
 
-------- Connect Metrics --------------------------------------------------------------------------- 
[--] Connect is disabled. 
 
-------- Galera Metrics ---------------------------------------------------------------------------- 
[--] Galera is disabled. 
 
-------- Replication Metrics ----------------------------------------------------------------------- 
[--] Galera Synchronous replication: NO 
[--] This server is acting as master for 1 server(s). 
[--] No replication setup for this server. 
 
-------- Recommendations --------------------------------------------------------------------------- 
General recommendations: 
    Restrict Host for user@% to user@SpecificDNSorIp 
    Reduce your overall MySQL memory footprint for system stability 
    Dedicate this server to your database for highest performance. 
    Increasing the query_cache size over 128M may reduce performance 
    Adjust your join queries to always utilize indexes 
Variables to adjust: 
  *** MySQL's maximum memory usage is dangerously high *** 
  *** Add RAM before increasing MySQL buffer variables *** 
    query_cache_type (=0) 
    query_cache_limit (> 2M, or use smaller result sets) 
    query_cache_size (> 128M) [see warning above] 
    join_buffer_size (> 8.0M, or always use indexes with joins) 
    innodb_log_file_size should be equals to 1/4 of buffer pool size (=1G) if possible. 
    innodb_buffer_pool_instances(=5)

MariaDB [(none)]> SHOW STATUS LIKE 'Qcache%'; 
+-------------------------+----------+ 
| Variable_name           | Value    | 
+-------------------------+----------+ 
| Qcache_free_blocks      | 14380    | 
| Qcache_free_memory      | 35054664 | 
| Qcache_hits             | 9778972  | 
| Qcache_inserts          | 6256712  | 
| Qcache_lowmem_prunes    | 171581   | 
| Qcache_not_cached       | 18163532 | 
| Qcache_queries_in_cache | 18775    | 
| Qcache_total_blocks     | 60116    | 
+-------------------------+----------+