WordPress Plugin: PHP Best Practice - php

Question

I have written a wordpress plugin which reads the value from an ACF field and outputs an image. The image is fetched through a shortcode.
I am a beginner and have some questions about this:
Is this approach heavy on performance?
Which solution would be best practice or more efficient?
Is there a possibility to optimize the code of the plugin?
For example, wouldnt it be better to set the images "globally".
If an image changes, I have to change it everywhere, and that's a lot of work.
$auswahl = get_field('dunstesse_energielabel');
if( $auswahl == 'A'){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-A-re.png">' ;
} else if ( $auswahl == 'B' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-B-re.png">' ;
} else if ( $auswahl == 'C' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-C-re.png">' ;
} else if ( $auswahl == 'D' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-D-re.png">' ;
} else if ( $auswahl == 'E' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-E-re.png">' ;
} else if ( $auswahl == 'F' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-F-re.png">' ;
} else if ( $auswahl == 'G' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-G-re.png">' ;
}
return $result;
}
add_shortcode('getEnergieDunstesse' , 'get_energie_dunstesse');
function get_energie_flachschirmhaube() {
$auswahl = get_field('flachschimhaube_energielabel');
if( $auswahl == 'A'){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-A-re.png">' ;
} else if ( $auswahl == 'B' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-B-re.png">' ;
} else if ( $auswahl == 'C' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-C-re.png">' ;
} else if ( $auswahl == 'D' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-D-re.png">' ;
} else if ( $auswahl == 'E' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-E-re.png">' ;
} else if ( $auswahl == 'F' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-F-re.png">' ;
} else if ( $auswahl == 'G' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-G-re.png">' ;
}
return $result;
}
add_shortcode('getEnergieFlachschirmhaube' , 'get_energie_flachschirmhaube');
function get_energie_induktion() {
$auswahl = get_field('induktions-kochfeld_energielabel');
if( $auswahl == 'A'){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-A-re.png">' ;
} else if ( $auswahl == 'B' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-B-re.png">' ;
} else if ( $auswahl == 'C' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-C-re.png">' ;
} else if ( $auswahl == 'D' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-D-re.png">' ;
} else if ( $auswahl == 'E' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-E-re.png">' ;
} else if ( $auswahl == 'F' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-F-re.png">' ;
} else if ( $auswahl == 'G' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-G-re.png">' ;
}
return $result;
}
add_shortcode('getEnergieInduktion' , 'get_energie_induktion');
function get_energie_glaskeramik() {
$auswahl = get_field('glaskeramik-kochfeld_energielabel');
if( $auswahl == 'A'){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-A-re.png">' ;
} else if ( $auswahl == 'B' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-B-re.png">' ;
} else if ( $auswahl == 'C' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-C-re.png">' ;
} else if ( $auswahl == 'D' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-D-re.png">' ;
} else if ( $auswahl == 'E' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-E-re.png">' ;
} else if ( $auswahl == 'F' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-F-re.png">' ;
} else if ( $auswahl == 'G' ){
$result = '<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-G-re.png">' ;
}
return $result;
}
add_shortcode('getEnergieGlaskeramik' , 'get_energie_glaskeramik');

Answer 1

In the terms of the code readability you can refactor each function to this form:
function get_energie_induktion() {
$auswahl = get_field('induktions-kochfeld_energielabel');
$defaultValue = <your-default-value>
$allowedValues = ['A','B','C','D','E'];
return in_array($auswahl, $allowedValues) ?
'<img class="energie" src="/wp-content/uploads/EEK_Buttons_2021-'.$auswahl.'-re.png">'
: $defaultValue;
}
And for $defaultValue you need to specify what you want to return in case no allowed option has been chosen.
Regarding the performance it doesn't really matter. You don't optimize such things over readibility, because micro-optimization is bad optimization.