如何减少name的食欲？

大家好。有一个资源非常有限的小型 VPS - 只有 256Mb RAM。我在这个运行 CentOS 7 操作系统的 VPS 上安装了 PHP 7.3、NginX 和绑定 9.9.4-74。检查 top 命令的输出，我注意到 named 占用了非常大的 RAM - 25.2%

PID  USER  PR NI VIRT   RES   SHR  S %CPU %MEM TIME+   COMMAND
1509 named 20 0  170804 61476 3260 S 0.0  25.2 0:00.24 named

这是 named.conf 配置

acl "trusted" {
    127.0.0.1;
    SERVER_IP;
};

// these are just a list of ip's that I consider bogus and just ignore them
acl "fakeips" {
#        0.0.0.0/8;
};

options {
    listen-on port 53 { 127.0.0.1;SERVER_IP; };
    directory   "/var/named";
    dump-file   "/var/named/data/cache_dump.db";
    statistics-file "/var/named/data/named_stats.txt";
    memstatistics-file "/var/named/data/named_mem_stats.txt";
    allow-query { any; }; // Этот параметр указывает, кому разрешается подавать запросы к нашему серверу
    allow-query-cache { none; };
    allow-recursion { trusted; };
    allow-notify { trusted; };
    allow-transfer { trusted; };
    version "not currently available";
    blackhole { fakeips; };

    dnssec-enable yes;
    dnssec-validation yes;
    dnssec-lookaside auto;

    /* Path to ISC DLV key */
    bindkeys-file "/etc/named.iscdlv.key";

    managed-keys-directory "/var/named/dynamic";

    pid-file "/run/named/named.pid";
    session-keyfile "/run/named/session.key";
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

zone "." IN {
    type hint;
    file "named.ca";
};

include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

告诉我，有没有办法减少named的胃口？这样就不会影响VPS的速度。