I know this is off-topic for the "speed" issue, but I wanted to offer a
simpler way to generate the holes.

They're not hex-aligned like the examples above, but it still looks cool.

module PAT(){
outer_D=400.0;
inner_D=6.5;
offset=2.5;// adjust for space between rings
theta=6; // adjust for space between holes around rings
linear_extrude(50.0)
difference() { circle(outer_D,center=true,$fn=512);
union() {
circle(inner_D,center=true);
for (j=[1:floor(outer_D/(inner_Doffset))])
for (i=[1:thetaj]) rotate([0,0,360/(thetaj)i])
translate([inner_Doffsetj,0.0,0.0])
circle(inner_D,center=true);
}}

}
$fa = 12;
$fs = 1;
PAT();

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or go for honeycombs:

module PAT()  {
outer_D = 400.0;
inner_D = 6.5;
height  = 50;
offset = 2;    // adjust for space between rings
theta = 6;      // adjust for space between holes around rings
linear_extrude(h=height)
// make it all in 2D and extrude the result
difference() {
// disk
circle(outer_D,center=true,$fn=512);
// holes
union() {
circle(inner_D, center=true);
circle_count = floor(outer_D / (inner_Doffset));
for (j = [1:circle_count])
for (i = [1:thetaj])
rotate([0,0,360/(thetaj)i])
translate([inner_Doffsetj,0,0])
circle(inner_D, center=true);
}
}
}

// $fa = 12;
// $fs = 1;
$fn=6;
PAT();

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